ui/gfx/nine_image_painter.cc

   1 // Copyright 2014 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 "ui/gfx/nine_image_painter.h"
   6
   7 #include <limits>
   8
   9 #include "third_party/skia/include/core/SkPaint.h"
  10 #include "third_party/skia/include/core/SkRect.h"
  11 #include "third_party/skia/include/core/SkScalar.h"
  12 #include "ui/gfx/canvas.h"
  13 #include "ui/gfx/geometry/insets.h"
  14 #include "ui/gfx/geometry/rect.h"
  15 #include "ui/gfx/geometry/rect_conversions.h"
  16 #include "ui/gfx/geometry/safe_integer_conversions.h"
  17 #include "ui/gfx/image/image_skia_operations.h"
  18 #include "ui/gfx/scoped_canvas.h"
  19 #include "ui/gfx/skia_util.h"
  20
  21 namespace gfx {
  22
  23 namespace {
  24
  25 // The following functions calculate width and height of the image in pixels
  26 // for the scale factor.
  27 int ImageWidthInPixels(const ImageSkia& i, float scale) {
  28   if (i.isNull())
  29     return 0;
  30   ImageSkiaRep image_rep = i.GetRepresentation(scale);
  31   return image_rep.pixel_width() * scale / image_rep.scale();
  32 }
  33
  34 int ImageHeightInPixels(const ImageSkia& i, float scale) {
  35   if (i.isNull())
  36     return 0;
  37   ImageSkiaRep image_rep = i.GetRepresentation(scale);
  38   return image_rep.pixel_height() * scale / image_rep.scale();
  39 }
  40
  41 // Stretches the given image over the specified canvas area.
  42 void Fill(Canvas* c,
  43           const ImageSkia& i,
  44           int x,
  45           int y,
  46           int w,
  47           int h,
  48           const SkPaint& paint) {
  49   if (i.isNull())
  50     return;
  51   c->DrawImageIntInPixel(i, 0, 0, ImageWidthInPixels(i, c->image_scale()),
  52                          ImageHeightInPixels(i, c->image_scale()),
  53                          x, y, w, h, false, paint);
  54 }
  55
  56 }  // namespace
  57
  58 NineImagePainter::NineImagePainter(const std::vector<ImageSkia>& images) {
  59   DCHECK_EQ(arraysize(images_), images.size());
  60   for (size_t i = 0; i < arraysize(images_); ++i)
  61     images_[i] = images[i];
  62 }
  63
  64 NineImagePainter::NineImagePainter(const ImageSkia& image,
  65                                    const Insets& insets) {
  66   std::vector<gfx::Rect> regions;
  67   GetSubsetRegions(image, insets, &regions);
  68   DCHECK_EQ(9u, regions.size());
  69
  70   for (size_t i = 0; i < 9; ++i)
  71     images_[i] = ImageSkiaOperations::ExtractSubset(image, regions[i]);
  72 }
  73
  74 NineImagePainter::~NineImagePainter() {
  75 }
  76
  77 bool NineImagePainter::IsEmpty() const {
  78   return images_[0].isNull();
  79 }
  80
  81 Size NineImagePainter::GetMinimumSize() const {
  82   return IsEmpty() ? Size() : Size(
  83       images_[0].width() + images_[1].width() + images_[2].width(),
  84       images_[0].height() + images_[3].height() + images_[6].height());
  85 }
  86
  87 void NineImagePainter::Paint(Canvas* canvas, const Rect& bounds) {
  88   // When no alpha value is specified, use default value of 100% opacity.
  89   Paint(canvas, bounds, std::numeric_limits<uint8>::max());
  90 }
  91
  92 void NineImagePainter::Paint(Canvas* canvas,
  93                              const Rect& bounds,
  94                              const uint8 alpha) {
  95   if (IsEmpty())
  96     return;
  97
  98   ScopedCanvas scoped_canvas(canvas);
  99   canvas->Translate(bounds.OffsetFromOrigin());
 100
 101   // Get the current transform from the canvas and apply it to the logical
 102   // bounds passed in. This will give us the pixel bounds which can be used
 103   // to draw the images at the correct locations.
 104   // We should not scale the bounds by the canvas->image_scale() as that can be
 105   // different from the real scale in the canvas transform.
 106   SkRect bounds_in_pixels_f;
 107   if (!canvas->sk_canvas()->getTotalMatrix().mapRect(
 108           &bounds_in_pixels_f, RectToSkRect(gfx::Rect(bounds.size()))))
 109     return;  // Invalid transform.
 110
 111   SkIRect bounds_in_pixels;
 112   bounds_in_pixels_f.dround(&bounds_in_pixels);
 113
 114   SkMatrix matrix = canvas->sk_canvas()->getTotalMatrix();
 115   matrix.setTranslateX(SkIntToScalar(bounds_in_pixels.x()));
 116   matrix.setTranslateY(SkIntToScalar(bounds_in_pixels.y()));
 117   canvas->sk_canvas()->setMatrix(matrix);
 118
 119   const int width_in_pixels = bounds_in_pixels.width();
 120   const int height_in_pixels = bounds_in_pixels.height();
 121   const float scale_x = matrix.getScaleX();
 122   const float scale_y = matrix.getScaleY();
 123
 124   // In case the corners and edges don't all have the same width/height, we draw
 125   // the center first, and extend it out in all directions to the edges of the
 126   // images with the smallest widths/heights.  This way there will be no
 127   // unpainted areas, though some corners or edges might overlap the center.
 128   int i0w = ImageWidthInPixels(images_[0], scale_x);
 129   int i2w = ImageWidthInPixels(images_[2], scale_x);
 130   int i3w = ImageWidthInPixels(images_[3], scale_x);
 131   int i5w = ImageWidthInPixels(images_[5], scale_x);
 132   int i6w = ImageWidthInPixels(images_[6], scale_x);
 133   int i8w = ImageWidthInPixels(images_[8], scale_x);
 134
 135   int i4x = std::min(std::min(i0w, i3w), i6w);
 136   int i4w = width_in_pixels - i4x - std::min(std::min(i2w, i5w), i8w);
 137
 138   int i0h = ImageHeightInPixels(images_[0], scale_y);
 139   int i1h = ImageHeightInPixels(images_[1], scale_y);
 140   int i2h = ImageHeightInPixels(images_[2], scale_y);
 141   int i6h = ImageHeightInPixels(images_[6], scale_y);
 142   int i7h = ImageHeightInPixels(images_[7], scale_y);
 143   int i8h = ImageHeightInPixels(images_[8], scale_y);
 144
 145   int i4y = std::min(std::min(i0h, i1h), i2h);
 146   int i4h = height_in_pixels - i4y - std::min(std::min(i6h, i7h), i8h);
 147
 148   SkPaint paint;
 149   paint.setAlpha(alpha);
 150
 151   Fill(canvas, images_[4], i4x, i4y, i4w, i4h, paint);
 152
 153   Fill(canvas, images_[0], 0, 0, i0w, i0h, paint);
 154
 155   Fill(canvas, images_[1], i0w, 0, width_in_pixels - i0w - i2w, i1h, paint);
 156
 157   Fill(canvas, images_[2], width_in_pixels - i2w, 0, i2w, i2h, paint);
 158
 159   Fill(canvas, images_[3], 0, i0h, i3w, height_in_pixels - i0h - i6h, paint);
 160
 161   Fill(canvas, images_[5], width_in_pixels - i5w, i2h, i5w,
 162        height_in_pixels - i2h - i8h, paint);
 163
 164   Fill(canvas, images_[6], 0, height_in_pixels - i6h, i6w, i6h, paint);
 165
 166   Fill(canvas, images_[7], i6w, height_in_pixels - i7h,
 167        width_in_pixels - i6w - i8w, i7h, paint);
 168
 169   Fill(canvas, images_[8], width_in_pixels - i8w, height_in_pixels - i8h, i8w,
 170        i8h, paint);
 171 }
 172
 173 // static
 174 void NineImagePainter::GetSubsetRegions(const ImageSkia& image,
 175                                         const Insets& insets,
 176                                         std::vector<Rect>* regions) {
 177   DCHECK_GE(image.width(), insets.width());
 178   DCHECK_GE(image.height(), insets.height());
 179
 180   std::vector<Rect> result(9);
 181
 182   const int x[] = {
 183       0, insets.left(), image.width() - insets.right(), image.width()};
 184   const int y[] = {
 185       0, insets.top(), image.height() - insets.bottom(), image.height()};
 186
 187   for (size_t j = 0; j < 3; ++j) {
 188     for (size_t i = 0; i < 3; ++i) {
 189       result[i + j * 3] = Rect(x[i], y[j], x[i + 1] - x[i], y[j + 1] - y[j]);
 190     }
 191   }
 192   result.swap(*regions);
 193 }
 194
 195 }  // namespace gfx