Make Mac pinch thresholding apply only to zoom (Chromium side)

content/browser/renderer_host/render_widget_host_view_mac.mm

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/renderer_host/render_widget_host_view_mac.h"
 
 #import <objc/runtime.h>
 #include <OpenGL/gl.h>
 #include <QuartzCore/QuartzCore.h>
 
@@ skipping 535 matching lines @@
 ///////////////////////////////////////////////////////////////////////////////
 // RenderWidgetHostViewMac, public:
 
 RenderWidgetHostViewMac::RenderWidgetHostViewMac(RenderWidgetHost* widget,
                                                  bool is_guest_view_hack)
     : render_widget_host_(RenderWidgetHostImpl::From(widget)),
       text_input_type_(ui::TEXT_INPUT_TYPE_NONE),
       can_compose_inline_(true),
       browser_compositor_state_(BrowserCompositorDestroyed),
       browser_compositor_placeholder_(new BrowserCompositorMacPlaceholder),
+      page_is_at_scale_one_(true),
       is_loading_(false),
       allow_pause_for_resize_or_repaint_(true),
       is_guest_view_hack_(is_guest_view_hack),
       fullscreen_parent_host_view_(NULL),
       weak_factory_(this) {
   // |cocoa_view_| owns us and we will be deleted when |cocoa_view_|
   // goes away.  Since we autorelease it, our caller must put
   // |GetNativeView()| into the view hierarchy right after calling us.
   cocoa_view_ = [[[RenderWidgetHostViewCocoa alloc]
                   initWithRenderWidgetHostViewMac:this] autorelease];
@@ skipping 894 matching lines @@
         desired_size);
   }
   return false;
 }
 
 void RenderWidgetHostViewMac::OnSwapCompositorFrame(
     uint32 output_surface_id, scoped_ptr<cc::CompositorFrame> frame) {
   TRACE_EVENT0("browser", "RenderWidgetHostViewMac::OnSwapCompositorFrame");
 
   last_scroll_offset_ = frame->metadata.root_scroll_offset;
+
+  page_is_at_scale_one_ = (frame->metadata.page_scale_factor == 1);

[aelias_OOO_until_Jul13, 2015/05/11 18:32:32]

Please check for "== min_page_scale_factor" instead, that's a bit more generic
and future-proof, and rename the variable to page_at_minimum_scale_.

[ccameron, 2015/05/11 19:21:43]

If we end up doing the rubber-band bounce for pinch-zoom, then we will probably
want one. But, setting it to minimum page scale for now.

[aelias_OOO_until_Jul13, 2015/05/11 21:22:34]

If we do, I would probably favor storing the "overpinched" scale in a separate
field, like you did for scrolling and for similar reasons, so this would still
work.

+
   if (frame->delegated_frame_data) {
     float scale_factor = frame->metadata.device_scale_factor;
 
     // Compute the frame size based on the root render pass rect size.
     cc::RenderPass* root_pass =
         frame->delegated_frame_data->render_pass_list.back();
     gfx::Size pixel_size = root_pass->output_rect.size();
     gfx::Size dip_size = gfx::ConvertSizeToDIP(scale_factor, pixel_size);
 
     root_layer_->SetBounds(gfx::Rect(dip_size));
@@ skipping 264 matching lines @@
   self = [super initWithFrame:NSZeroRect];
   if (self) {
     self.acceptsTouchEvents = YES;
     editCommand_helper_.reset(new RenderWidgetHostViewMacEditCommandHelper);
     editCommand_helper_->AddEditingSelectorsToClass([self class]);
 
     renderWidgetHostView_.reset(r);
     canBeKeyView_ = YES;
     opaque_ = YES;
     focusedPluginIdentifier_ = -1;
-    lastUsedPinchEventTimestamp_ = 0;
+    pinchHasReachedZoomThreshold_ = false;
 
     // OpenGL support:
     if ([self respondsToSelector:
         @selector(setWantsBestResolutionOpenGLSurface:)]) {
       [self setWantsBestResolutionOpenGLSurface:YES];
     }
     [[NSNotificationCenter defaultCenter]
         addObserver:self
            selector:@selector(didChangeScreenParameters:)
                name:NSApplicationDidChangeScreenParametersNotification
@@ skipping 511 matching lines @@
   if (endWheelMonitor_) {
     [NSEvent removeMonitor:endWheelMonitor_];
     endWheelMonitor_ = nil;
   }
 }
 
 - (void)beginGestureWithEvent:(NSEvent*)event {
   [responderDelegate_ beginGestureWithEvent:event];
   gestureBeginEvent_.reset(
       new WebGestureEvent(WebInputEventFactory::gestureEvent(event, self)));
-  unusedPinchAmount_ = 0;
+
+  // If more than 1 second has passed since the last pinch gesture ended, reset

[aelias_OOO_until_Jul13, 2015/05/11 18:32:32]

This comment is out of date.

[ccameron, 2015/05/11 19:21:43]

Done.

+  // the zoom threshold levels.
+  if (renderWidgetHostView_->page_is_at_scale_one_) {
+    pinchHasReachedZoomThreshold_ = false;
+    pinchUnusedAmount_ = 1;
+  }
 }
 
 - (void)endGestureWithEvent:(NSEvent*)event {
   [responderDelegate_ endGestureWithEvent:event];
   gestureBeginEvent_.reset();
 
   if (!renderWidgetHostView_->render_widget_host_)
     return;
 
   if (gestureBeginPinchSent_) {
     WebGestureEvent endEvent(WebInputEventFactory::gestureEvent(event, self));
     endEvent.type = WebInputEvent::GesturePinchEnd;
     renderWidgetHostView_->render_widget_host_->ForwardGestureEvent(endEvent);
     gestureBeginPinchSent_ = NO;
-    lastUsedPinchEventTimestamp_ = [event timestamp];
   }
 }
 
 - (void)touchesMovedWithEvent:(NSEvent*)event {
   [responderDelegate_ touchesMovedWithEvent:event];
 }
 
 - (void)touchesBeganWithEvent:(NSEvent*)event {
   [responderDelegate_ touchesBeganWithEvent:event];
 }
@@ skipping 92 matching lines @@
 - (void)magnifyWithEvent:(NSEvent*)event {
   if (!renderWidgetHostView_->render_widget_host_)
     return;
 
   // If, due to nesting of multiple gestures (e.g, from multiple touch
   // devices), the beginning of the gesture has been lost, skip the remainder
   // of the gesture.
   if (!gestureBeginEvent_)
     return;
 
+  if (!pinchHasReachedZoomThreshold_) {
+      pinchUnusedAmount_ *= (1 + [event magnification]);
+      if (pinchUnusedAmount_ < 0.667 || pinchUnusedAmount_ > 1.5)
+          pinchHasReachedZoomThreshold_ = true;
+  }
+
   // Send a GesturePinchBegin event if none has been sent yet.
   if (!gestureBeginPinchSent_) {
-    // If less than 1 second has passed since an intentional pinch zoom
-    // was done, don't threshold zooms, because subsequent zooms are likely
-    // intentional.
-    const NSTimeInterval kSecondsUntilZoomThresholdReEnabled = 1;
-    if ([event timestamp] - lastUsedPinchEventTimestamp_ >
-        kSecondsUntilZoomThresholdReEnabled) {
-      // Require that a 40% zoom be hit before actually zooming the page,
-      // to avoid accidental zooms.
-      // http://crbug.com/478981
-      unusedPinchAmount_ += [event magnification];
-      if (unusedPinchAmount_ > -0.4 && unusedPinchAmount_ < 0.4)
-        return;
-    }
-
     WebGestureEvent beginEvent(*gestureBeginEvent_);
     beginEvent.type = WebInputEvent::GesturePinchBegin;
     renderWidgetHostView_->render_widget_host_->ForwardGestureEvent(beginEvent);
     gestureBeginPinchSent_ = YES;
   }
 
   // Send a GesturePinchUpdate event.
-  const WebGestureEvent& updateEvent =
+  WebGestureEvent updateEvent =
       WebInputEventFactory::gestureEvent(event, self);
+  updateEvent.data.pinchUpdate.zoomDisabled = !pinchHasReachedZoomThreshold_;
   renderWidgetHostView_->render_widget_host_->ForwardGestureEvent(updateEvent);
 }
 
 - (void)viewWillMoveToWindow:(NSWindow*)newWindow {
   NSWindow* oldWindow = [self window];
 
   NSNotificationCenter* notificationCenter =
       [NSNotificationCenter defaultCenter];
 
   // Backing property notifications crash on 10.6 when building with the 10.7
@@ skipping 1036 matching lines @@
 
 // "-webkit-app-region: drag | no-drag" is implemented on Mac by excluding
 // regions that are not draggable. (See ControlRegionView in
 // native_app_window_cocoa.mm). This requires the render host view to be
 // draggable by default.
 - (BOOL)mouseDownCanMoveWindow {
   return YES;
 }
 
 @end