From 5ccc1c9d048f9ea026f914837636311bd49dc769 Mon Sep 17 00:00:00 2001
From: Alex Merry <dev@randomguy3.me.uk>
Date: Sun, 4 Aug 2013 15:00:58 +0100
Subject: GTK: holding down ctrl pans, regardless of tool

If the user presses the LMB whilst holding ctrl, we bypass the tool and
enter panning mode, where dragging the mouse moves around the graph,
until the LMB is released.
---
 tikzit/src/gtk/GraphEditorPanel.m | 66 +++++++++++++++++++++++++++------------
 1 file changed, 46 insertions(+), 20 deletions(-)

diff --git a/tikzit/src/gtk/GraphEditorPanel.m b/tikzit/src/gtk/GraphEditorPanel.m
index c87e53e..c1fdffd 100644
--- a/tikzit/src/gtk/GraphEditorPanel.m
+++ b/tikzit/src/gtk/GraphEditorPanel.m
@@ -29,11 +29,17 @@
 @class GraphRenderer;
 @class WidgetSurface;
 
+static const InputMask zoomPanMask = ControlMask;
+
 /**
- * Mostly just a multiplexer
+ * Mostly just a multiplexer, but also handles zoom and pan
+ * when ctrl is held
  */
 @interface GraphInputHandler : NSObject<InputDelegate> {
     GraphEditorPanel *panel;
+    NSPoint           dragOrigin;
+    NSPoint           oldGraphOrigin;
+    BOOL              zoomPanActive;
 }
 - (id) initForPanel:(GraphEditorPanel*)p;
 @end
@@ -68,6 +74,9 @@
     [super dealloc];
 }
 
+- (GraphRenderer*) renderer {
+    return renderer;
+}
 - (TikzDocument*) document {
     return [renderer document];
 }
@@ -135,12 +144,19 @@
     [super dealloc];
 }
 
-// FIXME: use a local copy of HandTool to implement CTRL-dragging
+// FIXME: share code with HandTool?
 - (void) mousePressAt:(NSPoint)pos withButton:(MouseButton)button andMask:(InputMask)mask {
-    [panel grabTool];
-    id<Tool> tool = [panel activeTool];
-    if ([tool respondsToSelector:@selector(mousePressAt:withButton:andMask:)]) {
-        [tool mousePressAt:pos withButton:button andMask:mask];
+    if (mask == zoomPanMask && button == LeftButton) {
+        dragOrigin = pos;
+        oldGraphOrigin = [[[panel renderer] transformer] origin];
+        zoomPanActive = YES;
+    } else {
+        zoomPanActive = NO;
+        [panel grabTool];
+        id<Tool> tool = [panel activeTool];
+        if ([tool respondsToSelector:@selector(mousePressAt:withButton:andMask:)]) {
+            [tool mousePressAt:pos withButton:button andMask:mask];
+        }
     }
 }
 
@@ -153,33 +169,43 @@
 }
 
 - (void) mouseReleaseAt:(NSPoint)pos withButton:(MouseButton)button andMask:(InputMask)mask {
-    if (![panel hasTool])
-        return;
-    id<Tool> tool = [panel activeTool];
-    if ([tool respondsToSelector:@selector(mouseReleaseAt:withButton:andMask:)]) {
-        [tool mouseReleaseAt:pos withButton:button andMask:mask];
+    if (zoomPanActive && button == LeftButton) {
+        zoomPanActive = NO;
+    } else if ([panel hasTool]) {
+        id<Tool> tool = [panel activeTool];
+        if ([tool respondsToSelector:@selector(mouseReleaseAt:withButton:andMask:)]) {
+            [tool mouseReleaseAt:pos withButton:button andMask:mask];
+        }
     }
 }
 
 - (void) mouseMoveTo:(NSPoint)pos withButtons:(MouseButton)buttons andMask:(InputMask)mask {
-    if (![panel hasTool])
-        return;
-    id<Tool> tool = [panel activeTool];
-    if ([tool respondsToSelector:@selector(mouseMoveTo:withButtons:andMask:)]) {
-        [tool mouseMoveTo:pos withButtons:buttons andMask:mask];
+    if (zoomPanActive && (buttons & LeftButton)) {
+        NSPoint newGraphOrigin = oldGraphOrigin;
+        newGraphOrigin.x += pos.x - dragOrigin.x;
+        newGraphOrigin.y += pos.y - dragOrigin.y;
+        [[[panel renderer] transformer] setOrigin:newGraphOrigin];
+        [[panel renderer] invalidateGraph];
+    } else if ([panel hasTool]) {
+        id<Tool> tool = [panel activeTool];
+        if ([tool respondsToSelector:@selector(mouseMoveTo:withButtons:andMask:)]) {
+            [tool mouseMoveTo:pos withButtons:buttons andMask:mask];
+        }
     }
 }
 
 - (void) mouseScrolledAt:(NSPoint)pos inDirection:(ScrollDirection)dir withMask:(InputMask)mask {
-    id<Tool> tool = [panel activeTool];
-    if (mask == ControlMask) {
+    if (mask == zoomPanMask) {
         if (dir == ScrollUp) {
             [panel zoomInAboutPoint:pos];
         } else if (dir == ScrollDown) {
             [panel zoomOutAboutPoint:pos];
         }
-    } else if ([panel hasTool] && [tool respondsToSelector:@selector(mouseScrolledAt:inDirection:withMask:)]) {
-        [tool mouseScrolledAt:pos inDirection:dir withMask:mask];
+    } else {
+        id<Tool> tool = [panel activeTool];
+        if ([panel hasTool] && [tool respondsToSelector:@selector(mouseScrolledAt:inDirection:withMask:)]) {
+            [tool mouseScrolledAt:pos inDirection:dir withMask:mask];
+        }
     }
 }
 
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