refactor: group viewport/zoom/pan state into a Viewport sub-struct

The visible-window + pan-anchor state was 10 flat fields (viewStart, viewEnd,
freqView*, pan*) used densely throughout the zoom/pan/scrollbar code. Group
them into a Viewport sub-struct (app.view.*).

Rename anchored strictly to 'app.' so ScopeView's own view->viewStart/viewEnd
(same field names) are untouched. Settled render verified pixel-identical
(AE=0); End/zoom path verified via injected key input.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/render.c

@@ -283,7 +283,7 @@ void DrawLabels(Rectangle bounds)
     // Time labels
     for (int i = 0; i <= 10; i++) {
         float t = (float)i / 10;
-        float timeSec = (app.viewStart + t * (app.viewEnd - app.viewStart)) * app.signal.duration;
+        float timeSec = (app.view.start + t * (app.view.end - app.view.start)) * app.signal.duration;
         float x = bounds.x + t * bounds.width;
         char label[32];
         if (timeSec >= 60) sprintf(label, "%d:%02d", (int)(timeSec / 60), (int)(timeSec) % 60);
@@ -293,8 +293,8 @@ void DrawLabels(Rectangle bounds)
 
     // Frequency labels adapted to current zoom level
     float maxFreq = (float)app.signal.sampleRate / 2.0f;
-    float freqMin = app.freqViewStart * maxFreq;
+    float freqMin = app.view.freqStart * maxFreq;
-    float freqMax = app.freqViewEnd * maxFreq;
+    float freqMax = app.view.freqEnd * maxFreq;
 
     // Choose tick spacing based on zoom range
     float freqRange = freqMax - freqMin;
@@ -348,13 +348,13 @@ void DrawSelection(Rectangle bounds)
     Color overlayColor = Fade(BLACK, 0.25f);  // Lighter overlay
     
     // Convert signal coordinates to viewport coordinates
-    float viewWidth = app.viewEnd - app.viewStart;
+    float viewWidth = app.view.end - app.view.start;
-    float freqWidth = app.freqViewEnd - app.freqViewStart;
+    float freqWidth = app.view.freqEnd - app.view.freqStart;
     
-    float selStartX = bounds.x + ((app.sel.timeStart - app.viewStart) / viewWidth) * bounds.width;
+    float selStartX = bounds.x + ((app.sel.timeStart - app.view.start) / viewWidth) * bounds.width;
-    float selEndX = bounds.x + ((app.sel.timeEnd - app.viewStart) / viewWidth) * bounds.width;
+    float selEndX = bounds.x + ((app.sel.timeEnd - app.view.start) / viewWidth) * bounds.width;
-    float selStartY = bounds.y + bounds.height - ((app.sel.freqEnd - app.freqViewStart) / freqWidth) * bounds.height;
+    float selStartY = bounds.y + bounds.height - ((app.sel.freqEnd - app.view.freqStart) / freqWidth) * bounds.height;
-    float selEndY = bounds.y + bounds.height - ((app.sel.freqStart - app.freqViewStart) / freqWidth) * bounds.height;
+    float selEndY = bounds.y + bounds.height - ((app.sel.freqStart - app.view.freqStart) / freqWidth) * bounds.height;
     
     // Clamp to viewport bounds
     selStartX = fmaxf(bounds.x, fminf(bounds.x + bounds.width, selStartX));
@@ -443,13 +443,13 @@ void DrawSelectionDrag(Rectangle bounds)
         (app.sel.isDragging && !IsMouseButtonDown(MOUSE_LEFT_BUTTON))) return;
     
     // Convert signal coordinates to viewport coordinates
-    float viewWidth = app.viewEnd - app.viewStart;
+    float viewWidth = app.view.end - app.view.start;
-    float freqWidth = app.freqViewEnd - app.freqViewStart;
+    float freqWidth = app.view.freqEnd - app.view.freqStart;
     
-    float selStartX = bounds.x + ((app.sel.timeStart - app.viewStart) / viewWidth) * bounds.width;
+    float selStartX = bounds.x + ((app.sel.timeStart - app.view.start) / viewWidth) * bounds.width;
-    float selEndX = bounds.x + ((app.sel.timeEnd - app.viewStart) / viewWidth) * bounds.width;
+    float selEndX = bounds.x + ((app.sel.timeEnd - app.view.start) / viewWidth) * bounds.width;
-    float selStartY = bounds.y + bounds.height - ((app.sel.freqEnd - app.freqViewStart) / freqWidth) * bounds.height;
+    float selStartY = bounds.y + bounds.height - ((app.sel.freqEnd - app.view.freqStart) / freqWidth) * bounds.height;
-    float selEndY = bounds.y + bounds.height - ((app.sel.freqStart - app.freqViewStart) / freqWidth) * bounds.height;
+    float selEndY = bounds.y + bounds.height - ((app.sel.freqStart - app.view.freqStart) / freqWidth) * bounds.height;
     
     // Clamp to viewport bounds
     selStartX = fmaxf(bounds.x, fminf(bounds.x + bounds.width, selStartX));
@@ -539,8 +539,8 @@ void DrawPlayhead(Rectangle bounds)
     if (!app.isPlaying || app.playheadT < 0.0f || app.playheadT > 1.0f) return;
 
     float timePos = app.sel.timeStart + app.playheadT * (app.sel.timeEnd - app.sel.timeStart);
-    float viewWidth = app.viewEnd - app.viewStart;
+    float viewWidth = app.view.end - app.view.start;
-    float t = (timePos - app.viewStart) / viewWidth;
+    float t = (timePos - app.view.start) / viewWidth;
     float x = bounds.x + t * bounds.width;
 
     // Clamp to bounds

src/spectrogram.c

@@ -119,7 +119,7 @@ void ResetForNewSignal(void)
     FreeAllCacheEntries(&app.fftCache);
 
     // Reset view + selection to full range.
-    app.viewStart = 0.0f; app.viewEnd = 1.0f;
+    app.view.start = 0.0f; app.view.end = 1.0f;
     ClearSelection();
 
     // Invalidate the cached visible texture.
@@ -142,15 +142,15 @@ static void ActionExport(void)         { ExportPNG(&app, app.exportDir); }
 
 static void ActionResetView(void)
 {
-    app.viewStart = 0.0f; app.viewEnd = 1.0f;
+    app.view.start = 0.0f; app.view.end = 1.0f;
-    app.freqViewStart = 0.0f; app.freqViewEnd = 1.0f;
+    app.view.freqStart = 0.0f; app.view.freqEnd = 1.0f;
     app.visibleTextureValid = false;
 }
 
 static void ActionZoomToStart(void)
 {
-    app.viewStart = 0.0f;
+    app.view.start = 0.0f;
-    app.viewEnd = 0.1f;
+    app.view.end = 0.1f;
     app.visibleTextureValid = false;
 }
 
@@ -224,8 +224,8 @@ int main(int argc, char* argv[])
     
     app.sel.timeStart = 0.0f; app.sel.timeEnd = 1.0f;
     app.sel.freqStart = 0.0f; app.sel.freqEnd = 1.0f;
-    app.viewStart = 0.0f; app.viewEnd = 1.0f;
+    app.view.start = 0.0f; app.view.end = 1.0f;
-    app.freqViewStart = 0.0f; app.freqViewEnd = 1.0f;
+    app.view.freqStart = 0.0f; app.view.freqEnd = 1.0f;
     app.showGrid = true;
     app.colormap = COLORMAP_INFERNO;
     app.amplitudeMode = SCALE_RELATIVE;
@@ -359,31 +359,31 @@ int main(int argc, char* argv[])
                     
                     // --- Time axis zoom (around cursor X) ---
                     float mouseT = (GetMousePosition().x - viewBounds.x) / viewBounds.width;
-                    mouseT = app.viewStart + mouseT * (app.viewEnd - app.viewStart);
+                    mouseT = app.view.start + mouseT * (app.view.end - app.view.start);
-                    float viewWidth = app.viewEnd - app.viewStart;
+                    float viewWidth = app.view.end - app.view.start;
                     float newWidth = viewWidth * zoomFactor;
                     if (newWidth < 0.02f) newWidth = 0.02f;
                     if (newWidth > 1.0f) newWidth = 1.0f;
-                    float leftOfMouse = mouseT - app.viewStart;
+                    float leftOfMouse = mouseT - app.view.start;
-                    float rightOfMouse = app.viewEnd - mouseT;
+                    float rightOfMouse = app.view.end - mouseT;
-                    app.viewStart = mouseT - leftOfMouse * (newWidth / viewWidth);
+                    app.view.start = mouseT - leftOfMouse * (newWidth / viewWidth);
-                    app.viewEnd = mouseT + rightOfMouse * (newWidth / viewWidth);
+                    app.view.end = mouseT + rightOfMouse * (newWidth / viewWidth);
-                    if (app.viewStart < 0) { app.viewStart = 0; app.viewEnd = newWidth; }
+                    if (app.view.start < 0) { app.view.start = 0; app.view.end = newWidth; }
-                    if (app.viewEnd > 1) { app.viewEnd = 1; app.viewStart = 1 - newWidth; }
+                    if (app.view.end > 1) { app.view.end = 1; app.view.start = 1 - newWidth; }
                     
                     // --- Frequency axis zoom (around cursor Y) ---
                     float mouseF = 1.0f - (GetMousePosition().y - viewBounds.y) / viewBounds.height;
-                    mouseF = app.freqViewStart + mouseF * (app.freqViewEnd - app.freqViewStart);
+                    mouseF = app.view.freqStart + mouseF * (app.view.freqEnd - app.view.freqStart);
-                    float freqWidth = app.freqViewEnd - app.freqViewStart;
+                    float freqWidth = app.view.freqEnd - app.view.freqStart;
                     float newFreqWidth = freqWidth * zoomFactor;
                     if (newFreqWidth < 0.001f) newFreqWidth = 0.001f;
-                    float belowMouse = mouseF - app.freqViewStart;
+                    float belowMouse = mouseF - app.view.freqStart;
-                    float aboveMouse = app.freqViewEnd - mouseF;
+                    float aboveMouse = app.view.freqEnd - mouseF;
-                    app.freqViewStart = mouseF - belowMouse * (newFreqWidth / freqWidth);
+                    app.view.freqStart = mouseF - belowMouse * (newFreqWidth / freqWidth);
-                    app.freqViewEnd = mouseF + aboveMouse * (newFreqWidth / freqWidth);
+                    app.view.freqEnd = mouseF + aboveMouse * (newFreqWidth / freqWidth);
                     // Clamp to physical frequency limits [0, 1] — can't see beyond Nyquist or below 0 Hz
-                    if (app.freqViewStart < 0) { app.freqViewStart = 0; app.freqViewEnd = fminf(app.freqViewEnd, 1.0f); }
+                    if (app.view.freqStart < 0) { app.view.freqStart = 0; app.view.freqEnd = fminf(app.view.freqEnd, 1.0f); }
-                    if (app.freqViewEnd > 1) { app.freqViewEnd = 1; app.freqViewStart = fmaxf(app.freqViewStart, 0.0f); }
+                    if (app.view.freqEnd > 1) { app.view.freqEnd = 1; app.view.freqStart = fmaxf(app.view.freqStart, 0.0f); }
 
                     // Invalidate texture cache
                     app.visibleTextureValid = false;
@@ -393,51 +393,51 @@ int main(int argc, char* argv[])
             // Pan with Alt+drag or middle mouse button (pans both axes)
             bool canPan = IsKeyDown(KEY_LEFT_ALT) || IsKeyDown(KEY_RIGHT_ALT) || IsMouseButtonDown(MOUSE_BUTTON_MIDDLE);
             if (canPan && IsMouseButtonPressed(MOUSE_LEFT_BUTTON)) {
-                app.isPanning = true;
+                app.view.isPanning = true;
-                app.panStartPos = GetMousePosition();
+                app.view.panStartPos = GetMousePosition();
-                app.panStartViewStart = app.viewStart;
+                app.view.panStart = app.view.start;
-                app.panStartViewEnd = app.viewEnd;
+                app.view.panEnd = app.view.end;
-                app.panStartFreqViewStart = app.freqViewStart;
+                app.view.panFreqStart = app.view.freqStart;
-                app.panStartFreqViewEnd = app.freqViewEnd;
+                app.view.panFreqEnd = app.view.freqEnd;
             }
-            if (app.isPanning && IsMouseButtonDown(MOUSE_LEFT_BUTTON)) {
+            if (app.view.isPanning && IsMouseButtonDown(MOUSE_LEFT_BUTTON)) {
-                float dx = (GetMousePosition().x - app.panStartPos.x) / viewBounds.width;
+                float dx = (GetMousePosition().x - app.view.panStartPos.x) / viewBounds.width;
-                float dy = (GetMousePosition().y - app.panStartPos.y) / viewBounds.height;
+                float dy = (GetMousePosition().y - app.view.panStartPos.y) / viewBounds.height;
-                float viewWidth = app.panStartViewEnd - app.panStartViewStart;
+                float viewWidth = app.view.panEnd - app.view.panStart;
-                float freqWidth = app.panStartFreqViewEnd - app.panStartFreqViewStart;
+                float freqWidth = app.view.panFreqEnd - app.view.panFreqStart;
-                app.viewStart = app.panStartViewStart - dx * viewWidth;
+                app.view.start = app.view.panStart - dx * viewWidth;
-                app.viewEnd = app.panStartViewEnd - dx * viewWidth;
+                app.view.end = app.view.panEnd - dx * viewWidth;
-                if (app.viewStart < 0) { app.viewStart = 0; app.viewEnd = viewWidth; }
+                if (app.view.start < 0) { app.view.start = 0; app.view.end = viewWidth; }
-                if (app.viewEnd > 1) { app.viewEnd = 1; app.viewStart = 1 - viewWidth; }
+                if (app.view.end > 1) { app.view.end = 1; app.view.start = 1 - viewWidth; }
-                app.freqViewStart = app.panStartFreqViewStart + dy * freqWidth;
+                app.view.freqStart = app.view.panFreqStart + dy * freqWidth;
-                app.freqViewEnd = app.panStartFreqViewEnd + dy * freqWidth;
+                app.view.freqEnd = app.view.panFreqEnd + dy * freqWidth;
                 // Clamp to physical limits [0, 1]
-                if (app.freqViewStart < 0) {
+                if (app.view.freqStart < 0) {
-                    float actualWidth = app.freqViewEnd - app.freqViewStart;
+                    float actualWidth = app.view.freqEnd - app.view.freqStart;
-                    app.freqViewStart = 0;
+                    app.view.freqStart = 0;
-                    app.freqViewEnd = fminf(actualWidth, 1.0f);
+                    app.view.freqEnd = fminf(actualWidth, 1.0f);
                 }
-                if (app.freqViewEnd > 1) {
+                if (app.view.freqEnd > 1) {
-                    float actualWidth = app.freqViewEnd - app.freqViewStart;
+                    float actualWidth = app.view.freqEnd - app.view.freqStart;
-                    app.freqViewEnd = 1;
+                    app.view.freqEnd = 1;
-                    app.freqViewStart = fmaxf(1.0f - actualWidth, 0.0f);
+                    app.view.freqStart = fmaxf(1.0f - actualWidth, 0.0f);
                 }
-                if (app.freqViewStart < 0) app.freqViewStart = 0;
+                if (app.view.freqStart < 0) app.view.freqStart = 0;
-                if (app.freqViewEnd > 1) app.freqViewEnd = 1;
+                if (app.view.freqEnd > 1) app.view.freqEnd = 1;
                 app.visibleTextureValid = false;
             }
-            if (IsMouseButtonReleased(MOUSE_LEFT_BUTTON)) app.isPanning = false;
+            if (IsMouseButtonReleased(MOUSE_LEFT_BUTTON)) app.view.isPanning = false;
 
             // Foreground high-res: when user zooms in, compute missing
             // segments in the visible range immediately (responsive).
             // Background task handles the rest when idle.
             if (app.skipFactor > 1 && app.stft.numSegments > 0 && !app.bgFinished) {
-                float viewRange = app.viewEnd - app.viewStart;
+                float viewRange = app.view.end - app.view.start;
 
                 if (viewRange <= 0.25f) {
                     // Clamp to valid segment range
-                    int viewStartSeg = (int)(app.viewStart * app.stft.numSegments);
+                    int viewStartSeg = (int)(app.view.start * app.stft.numSegments);
-                    int viewEndSeg = (int)(app.viewEnd * app.stft.numSegments);
+                    int viewEndSeg = (int)(app.view.end * app.stft.numSegments);
                     if (viewStartSeg < 0) viewStartSeg = 0;
                     if (viewStartSeg >= app.stft.numSegments) viewStartSeg = app.stft.numSegments - 1;
                     if (viewEndSeg >= app.stft.numSegments) viewEndSeg = app.stft.numSegments - 1;
@@ -461,7 +461,7 @@ int main(int argc, char* argv[])
             // segments at full resolution. Pauses on any interaction.
             // Also kicks in when zoomed out (no foreground trigger) to fill
             // segments outside the view range.
-            bool isZoomedIn = (app.skipFactor > 1 && app.viewEnd - app.viewStart <= 0.25f);
+            bool isZoomedIn = (app.skipFactor > 1 && app.view.end - app.view.start <= 0.25f);
             if (app.isBgProcessing && !app.bgFinished && !IsUserInteracting()) {
                 int endSeg = app.bgHighResSeg + 50; // chunks of 50 segments
                 if (endSeg > app.stft.numSegments) endSeg = app.stft.numSegments;
@@ -562,10 +562,10 @@ int main(int argc, char* argv[])
         bool hoverInsideSelection = false;
         if (hasSelection && CheckCollisionPointRec(mousePos, selBounds)) {
             // Convert mouse position to signal coordinates
-            float viewWidth = app.viewEnd - app.viewStart;
+            float viewWidth = app.view.end - app.view.start;
-            float freqWidth = app.freqViewEnd - app.freqViewStart;
+            float freqWidth = app.view.freqEnd - app.view.freqStart;
-            float mouseTime = app.viewStart + ((mousePos.x - selBounds.x) / selBounds.width) * viewWidth;
+            float mouseTime = app.view.start + ((mousePos.x - selBounds.x) / selBounds.width) * viewWidth;
-            float mouseFreq = app.freqViewStart + (1.0f - (mousePos.y - selBounds.y) / selBounds.height) * freqWidth;
+            float mouseFreq = app.view.freqStart + (1.0f - (mousePos.y - selBounds.y) / selBounds.height) * freqWidth;
             
             if (mouseTime >= app.sel.timeStart && mouseTime <= app.sel.timeEnd &&
                 mouseFreq >= app.sel.freqStart && mouseFreq <= app.sel.freqEnd) {
@@ -614,17 +614,17 @@ int main(int argc, char* argv[])
                     float viewportT = (mousePos.x - selBounds.x) / selBounds.width;
                     float viewportF = 1.0f - (mousePos.y - selBounds.y) / selBounds.height;
                     
-                    app.sel.timeStart = Clamp(app.viewStart + viewportT * (app.viewEnd - app.viewStart), 0.0f, 1.0f);
+                    app.sel.timeStart = Clamp(app.view.start + viewportT * (app.view.end - app.view.start), 0.0f, 1.0f);
                     app.sel.timeEnd = app.sel.timeStart;
-                    app.sel.freqStart = Clamp(app.freqViewStart + viewportF * (app.freqViewEnd - app.freqViewStart), 0.0f, 1.0f);
+                    app.sel.freqStart = Clamp(app.view.freqStart + viewportF * (app.view.freqEnd - app.view.freqStart), 0.0f, 1.0f);
                     app.sel.freqEnd = app.sel.freqStart;
                 }
             }
             
             // Dragging existing selection
             if (app.sel.isDragging && IsMouseButtonDown(MOUSE_LEFT_BUTTON)) {
-                float viewWidth = app.viewEnd - app.viewStart;
+                float viewWidth = app.view.end - app.view.start;
-                float freqWidth = app.freqViewEnd - app.freqViewStart;
+                float freqWidth = app.view.freqEnd - app.view.freqStart;
                 
                 float dx = (mousePos.x - app.sel.dragStartPos.x) / selBounds.width;
                 float dy = (mousePos.y - app.sel.dragStartPos.y) / selBounds.height;
@@ -646,8 +646,8 @@ int main(int argc, char* argv[])
                 float viewportT = (mousePos.x - selBounds.x) / selBounds.width;
                 float viewportF = 1.0f - (mousePos.y - selBounds.y) / selBounds.height;
                 
-                app.sel.timeEnd = Clamp(app.viewStart + viewportT * (app.viewEnd - app.viewStart), 0.0f, 1.0f);
+                app.sel.timeEnd = Clamp(app.view.start + viewportT * (app.view.end - app.view.start), 0.0f, 1.0f);
-                app.sel.freqEnd = Clamp(app.freqViewStart + viewportF * (app.freqViewEnd - app.freqViewStart), 0.0f, 1.0f);
+                app.sel.freqEnd = Clamp(app.view.freqStart + viewportF * (app.view.freqEnd - app.view.freqStart), 0.0f, 1.0f);
             }
             
             if (IsMouseButtonReleased(MOUSE_LEFT_BUTTON)) {
@@ -837,13 +837,13 @@ int main(int argc, char* argv[])
             int imgHeight = app.spectrogramImage.height;
 
             // Calculate visible region (time and frequency)
-            int visibleStartX = (int)(app.viewStart * imgWidth);
+            int visibleStartX = (int)(app.view.start * imgWidth);
-            int visibleEndX = (int)(app.viewEnd * imgWidth);
+            int visibleEndX = (int)(app.view.end * imgWidth);
             int visibleWidth = visibleEndX - visibleStartX;
             
             // Frequency: 0 = bottom of image (bin 0), 1 = top of image (bin max)
-            int visibleStartY = (int)((1.0f - app.freqViewEnd) * imgHeight);
+            int visibleStartY = (int)((1.0f - app.view.freqEnd) * imgHeight);
-            int visibleEndY = (int)((1.0f - app.freqViewStart) * imgHeight);
+            int visibleEndY = (int)((1.0f - app.view.freqStart) * imgHeight);
             int visibleHeight = visibleEndY - visibleStartY;
 
             // Invalidate cache if view changed or texture not valid
@@ -889,15 +889,15 @@ int main(int argc, char* argv[])
             // Draw scrollbars
             // Horizontal scrollbar (time)
             DrawRectangleRec(hScrollbar, DARKGRAY);
-            float hThumbWidth = (app.viewEnd - app.viewStart) * hScrollbar.width;
+            float hThumbWidth = (app.view.end - app.view.start) * hScrollbar.width;
-            float hThumbX = hScrollbar.x + app.viewStart * hScrollbar.width;
+            float hThumbX = hScrollbar.x + app.view.start * hScrollbar.width;
             if (hThumbWidth < 10) hThumbWidth = 10;
             DrawRectangle(hThumbX, hScrollbar.y, hThumbWidth, hScrollbar.height, GRAY);
             
             // Vertical scrollbar (frequency)
             DrawRectangleRec(vScrollbar, DARKGRAY);
-            float vThumbHeight = (app.freqViewEnd - app.freqViewStart) * vScrollbar.height;
+            float vThumbHeight = (app.view.freqEnd - app.view.freqStart) * vScrollbar.height;
-            float vThumbY = vScrollbar.y + (1.0f - app.freqViewEnd) * vScrollbar.height;
+            float vThumbY = vScrollbar.y + (1.0f - app.view.freqEnd) * vScrollbar.height;
             if (vThumbHeight < 10) vThumbHeight = 10;
             DrawRectangle(vScrollbar.x, vThumbY, vScrollbar.width, vThumbHeight, GRAY);
 
@@ -909,37 +909,37 @@ int main(int argc, char* argv[])
             if (IsMouseButtonPressed(MOUSE_LEFT_BUTTON) && CheckCollisionPointRec(GetMousePosition(), hScrollbar)) {
                 draggingH = true;
                 dragStartPos = GetMousePosition();
-                dragStartViewStart = app.viewStart;
+                dragStartViewStart = app.view.start;
             }
             if (IsMouseButtonPressed(MOUSE_LEFT_BUTTON) && CheckCollisionPointRec(GetMousePosition(), vScrollbar)) {
                 draggingV = true;
                 dragStartPos = GetMousePosition();
-                dragStartFreqViewStart = app.freqViewStart;
+                dragStartFreqViewStart = app.view.freqStart;
             }
             if (draggingH && IsMouseButtonDown(MOUSE_LEFT_BUTTON)) {
                 float dx = (GetMousePosition().x - dragStartPos.x) / hScrollbar.width;
-                float viewWidth = app.viewEnd - app.viewStart;
+                float viewWidth = app.view.end - app.view.start;
-                app.viewStart = dragStartViewStart + dx;
+                app.view.start = dragStartViewStart + dx;
-                app.viewEnd = app.viewStart + viewWidth;
+                app.view.end = app.view.start + viewWidth;
-                if (app.viewStart < 0) { app.viewStart = 0; app.viewEnd = viewWidth; }
+                if (app.view.start < 0) { app.view.start = 0; app.view.end = viewWidth; }
-                if (app.viewEnd > 1) { app.viewEnd = 1; app.viewStart = 1 - viewWidth; }
+                if (app.view.end > 1) { app.view.end = 1; app.view.start = 1 - viewWidth; }
                 app.visibleTextureValid = false;
             }
             if (draggingV && IsMouseButtonDown(MOUSE_LEFT_BUTTON)) {
                 float dy = (GetMousePosition().y - dragStartPos.y) / vScrollbar.height;
-                float freqWidth = app.freqViewEnd - app.freqViewStart;
+                float freqWidth = app.view.freqEnd - app.view.freqStart;
-                app.freqViewStart = dragStartFreqViewStart - dy;
+                app.view.freqStart = dragStartFreqViewStart - dy;
-                app.freqViewEnd = app.freqViewStart + freqWidth;
+                app.view.freqEnd = app.view.freqStart + freqWidth;
-                if (app.freqViewStart < 0) {
+                if (app.view.freqStart < 0) {
-                    app.freqViewStart = 0;
+                    app.view.freqStart = 0;
-                    app.freqViewEnd = fminf(freqWidth, 1.0f);
+                    app.view.freqEnd = fminf(freqWidth, 1.0f);
                 }
-                if (app.freqViewEnd > 1) {
+                if (app.view.freqEnd > 1) {
-                    app.freqViewEnd = 1;
+                    app.view.freqEnd = 1;
-                    app.freqViewStart = fmaxf(1.0f - freqWidth, 0.0f);
+                    app.view.freqStart = fmaxf(1.0f - freqWidth, 0.0f);
                 }
-                if (app.freqViewStart < 0) app.freqViewStart = 0;
+                if (app.view.freqStart < 0) app.view.freqStart = 0;
-                if (app.freqViewEnd > 1) app.freqViewEnd = 1;
+                if (app.view.freqEnd > 1) app.view.freqEnd = 1;
                 app.visibleTextureValid = false;
             }
             if (IsMouseButtonReleased(MOUSE_LEFT_BUTTON)) { draggingH = false; draggingV = false; }
@@ -950,8 +950,8 @@ int main(int argc, char* argv[])
             DrawPlayhead(viewBounds);
             DrawLabels(viewBounds);
             float maxFreq = (float)app.signal.sampleRate / 2.0f;
-            float freqMin = app.freqViewStart * maxFreq;
+            float freqMin = app.view.freqStart * maxFreq;
-            float freqMax = app.freqViewEnd * maxFreq;
+            float freqMax = app.view.freqEnd * maxFreq;
             DrawTextScaled(TextFormat("Freq: %.0f-%.0f Hz", freqMin, freqMax),
                     viewBounds.x, viewBounds.y - 30, 20, LIGHTGRAY);
             
@@ -964,8 +964,8 @@ int main(int argc, char* argv[])
                 app.scopeView.width = viewBounds.width;
                 app.scopeView.height = (int)scopeHeight;
                 // Keep time view in sync with spectrogram view
-                app.scopeView.viewStart = app.viewStart;
+                app.scopeView.viewStart = app.view.start;
-                app.scopeView.viewEnd = app.viewEnd;
+                app.scopeView.viewEnd = app.view.end;
                 // Update waveform data
                 app.scopeView.data.samples = app.signal.samples;
                 app.scopeView.data.numSamples = app.signal.numSamples;

src/spectrogram_types.h

@@ -106,6 +106,17 @@ typedef struct {
     float dragFreqStart;        // selection freq start when the move began
 } Selection;
 
+// The visible window into the spectrogram (time + frequency), all 0-1
+// normalized, plus the range captured at the start of a pan drag.
+typedef struct {
+    float start, end;                 // visible time range
+    float freqStart, freqEnd;         // visible freq range (0 = 0 Hz, 1 = Nyquist)
+    bool isPanning;
+    float panStart, panEnd;           // time range captured when the pan began
+    float panFreqStart, panFreqEnd;   // freq range captured when the pan began
+    Vector2 panStartPos;              // mouse pos when the pan began
+} Viewport;
+
 typedef struct {
     AudioSignal signal;
     StftResult stft;
@@ -126,17 +137,8 @@ typedef struct {
     char exportDir[4096];
     char exportMessage[256];
 
-    // Viewport/zoom controls
+    // Visible viewport (time + frequency) and in-progress pan state.
-    float viewStart;      // 0-1, start of visible time region
+    Viewport view;
-    float viewEnd;        // 0-1, end of visible time region
-    float freqViewStart;  // 0-1, start of visible frequency region (0 = 0Hz)
-    float freqViewEnd;    // 0-1, end of visible frequency region (1 = Nyquist)
-    bool isPanning;
-    float panStartViewStart;
-    float panStartViewEnd;
-    float panStartFreqViewStart;
-    float panStartFreqViewEnd;
-    Vector2 panStartPos;
 
     // Cached visible texture
     Texture2D visibleTexture;