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