PDF Viewer pinch zoom: Update state for zoom in following a zoom out.

pdf/out_of_process_instance.cc

 // 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 "pdf/out_of_process_instance.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>  // for min/max()
@@ skipping 479 matching lines @@
     }
 
     if (pinch_phase == PINCH_UPDATE_ZOOM_OUT || pinch_phase == PINCH_END) {
       // We reraster on pinch zoom out in order to solve the invalid regions
       // that appear after zooming out.
       // On pinch end the scale is again 1.f and we request a reraster
       // in the new position.
       paint_manager_.ClearTransform();
       last_bitmap_smaller_ = false;
       needs_reraster_ = true;
+
+      // If we're zooming out, we need to update |starting_scroll_offset_| and
+      // |initial_zoom_ratio_|, in case the user continues the gesture by
+      // zooming in.
+      starting_scroll_offset_ = scroll_offset;

[bokan, 2017/03/28 14:26:26]

These two variables are the offset/zoom since last raster, right? Please update
the comment on starting_scroll_offset_ to make that more clear (and add a
similar comment on initial_zoom_ratio_) if that's right.

[Kevin McNee, 2017/03/28 22:55:26]

So it turns out that |initial_zoom_ratio_| is redundant since |zoom_| gives us
all the information we need, so I've gone ahead and removed it entirely. Also,
I've renamed |starting_scroll_offset_| to |scroll_offset_at_last_raster_| to
better describe its purpose.

Still LGTM?

+      initial_zoom_ratio_ = zoom_ratio;
     }
 
     // Bound the input parameters.
     zoom = std::max(kMinZoom, zoom);
     SetZoom(zoom);
     scroll_offset = BoundScrollOffsetToDocument(scroll_offset);
     engine_->ScrolledToXPosition(scroll_offset.x() * device_scale_);
     engine_->ScrolledToYPosition(scroll_offset.y() * device_scale_);
   } else if (type == kJSGetPasswordCompleteType &&
              dict.Get(pp::Var(kJSPassword)).is_string()) {
@@ skipping 1140 matching lines @@
     const pp::FloatPoint& scroll_offset) {
   float max_x = document_size_.width() * zoom_ - plugin_dip_size_.width();
   float x = std::max(std::min(scroll_offset.x(), max_x), 0.0f);
   float min_y = -top_toolbar_height_;
   float max_y = document_size_.height() * zoom_ - plugin_dip_size_.height();
   float y = std::max(std::min(scroll_offset.y(), max_y), min_y);
   return pp::FloatPoint(x, y);
 }
 
 }  // namespace chrome_pdf