src/content/renderer/disambiguation_popup_helper.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "content/renderer/disambiguation_popup_helper.h"
   6
   7 #include "third_party/WebKit/public/platform/WebRect.h"
   8 #include "ui/gfx/size_conversions.h"
   9
  10 using WebKit::WebRect;
  11 using WebKit::WebVector;
  12
  13 namespace {
  14
  15 // The amount of padding to add to the disambiguation popup to show
  16 // content around the possible elements, adding some context.
  17 const int kDisambiguationPopupPadding = 8;
  18
  19 // Constants used for fitting the disambiguation popup inside the bounds of
  20 // the view. Note that there are mirror constants in PopupZoomer.java.
  21 const int kDisambiguationPopupBoundsMargin = 25;
  22
  23 // The smallest allowable touch target used for disambiguation popup.
  24 // This value is used to determine the minimum amount we need to scale to
  25 // make all targets touchable.
  26 const int kDisambiguationPopupMinimumTouchSize = 40;
  27 const float kDisambiguationPopupMaxScale = 5.0;
  28 const float kDisambiguationPopupMinScale = 2.0;
  29
  30 // Compute the scaling factor to ensure the smallest touch candidate reaches
  31 // a certain clickable size after zooming
  32 float FindOptimalScaleFactor(const WebVector<WebRect>& target_rects,
  33                              float total_scale) {
  34   using std::min;
  35   using std::max;
  36   if (!target_rects.size())  // shall never reach
  37     return kDisambiguationPopupMinScale;
  38   float smallest_target = min(target_rects[0].width * total_scale,
  39                               target_rects[0].height * total_scale);
  40   for (size_t i = 1; i < target_rects.size(); i++) {
  41     smallest_target = min(smallest_target, target_rects[i].width * total_scale);
  42     smallest_target = min(smallest_target,
  43         target_rects[i].height * total_scale);
  44   }
  45   smallest_target = max(smallest_target, 1.0f);
  46   return min(kDisambiguationPopupMaxScale, max(kDisambiguationPopupMinScale,
  47       kDisambiguationPopupMinimumTouchSize / smallest_target)) * total_scale;
  48 }
  49
  50 void TrimEdges(int *e1, int *e2, int max_combined) {
  51   if (*e1 + *e2 <= max_combined)
  52     return;
  53
  54   if (std::min(*e1, *e2) * 2 >= max_combined)
  55     *e1 = *e2 = max_combined / 2;
  56   else if (*e1 > *e2)
  57     *e1 = max_combined - *e2;
  58   else
  59     *e2 = max_combined - *e1;
  60 }
  61
  62 // Ensure the disambiguation popup fits inside the screen,
  63 // clip the edges farthest to the touch point if needed.
  64 gfx::Rect CropZoomArea(const gfx::Rect& zoom_rect,
  65                        const gfx::Size& viewport_size,
  66                        const gfx::Point& touch_point,
  67                        float scale) {
  68   gfx::Size max_size = viewport_size;
  69   max_size.Enlarge(-2 * kDisambiguationPopupBoundsMargin,
  70                    -2 * kDisambiguationPopupBoundsMargin);
  71   max_size = ToCeiledSize(ScaleSize(max_size, 1.0 / scale));
  72
  73   int left = touch_point.x() - zoom_rect.x();
  74   int right = zoom_rect.right() - touch_point.x();
  75   int top = touch_point.y() - zoom_rect.y();
  76   int bottom = zoom_rect.bottom() - touch_point.y();
  77   TrimEdges(&left, &right, max_size.width());
  78   TrimEdges(&top, &bottom, max_size.height());
  79
  80   return gfx::Rect(touch_point.x() - left,
  81                    touch_point.y() - top,
  82                    left + right,
  83                    top + bottom);
  84 }
  85
  86 }  // namespace
  87
  88 namespace content {
  89
  90 float DisambiguationPopupHelper::ComputeZoomAreaAndScaleFactor(
  91     const gfx::Rect& tap_rect,
  92     const WebVector<WebRect>& target_rects,
  93     const gfx::Size& screen_size,
  94     const gfx::Size& visible_content_size,
  95     float total_scale,
  96     gfx::Rect* zoom_rect) {
  97   *zoom_rect = tap_rect;
  98   for (size_t i = 0; i < target_rects.size(); i++)
  99     zoom_rect->Union(gfx::Rect(target_rects[i]));
 100   zoom_rect->Inset(-kDisambiguationPopupPadding, -kDisambiguationPopupPadding);
 101
 102   zoom_rect->Intersect(gfx::Rect(visible_content_size));
 103
 104   float new_total_scale =
 105       FindOptimalScaleFactor(target_rects, total_scale);
 106   *zoom_rect = CropZoomArea(
 107       *zoom_rect, screen_size, tap_rect.CenterPoint(), new_total_scale);
 108
 109   return new_total_scale;
 110 }
 111
 112 }  // namespace content