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/rect_conversions.h"
  14 #include "ui/gfx/geometry/safe_integer_conversions.h"
  15 #include "ui/gfx/image/image_skia_operations.h"
  16 #include "ui/gfx/insets.h"
  17 #include "ui/gfx/rect.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   return i.GetRepresentation(c->image_scale()).pixel_width();
  29 }
  30
  31 int ImageHeightInPixels(const ImageSkia& i, Canvas* c) {
  32   return i.GetRepresentation(c->image_scale()).pixel_height();
  33 }
  34
  35 // Stretches the given image over the specified canvas area.
  36 void Fill(Canvas* c,
  37           const ImageSkia& i,
  38           int x,
  39           int y,
  40           int w,
  41           int h,
  42           const SkPaint& paint) {
  43   c->DrawImageIntInPixel(i, 0, 0, ImageWidthInPixels(i, c),
  44                          ImageHeightInPixels(i, c), x, y, w, h, false, paint);
  45 }
  46
  47 }  // namespace
  48
  49 NineImagePainter::NineImagePainter(const std::vector<ImageSkia>& images) {
  50   DCHECK_EQ(arraysize(images_), images.size());
  51   for (size_t i = 0; i < arraysize(images_); ++i)
  52     images_[i] = images[i];
  53 }
  54
  55 NineImagePainter::NineImagePainter(const ImageSkia& image,
  56                                    const Insets& insets) {
  57   DCHECK_GE(image.width(), insets.width());
  58   DCHECK_GE(image.height(), insets.height());
  59
  60   // Extract subsets of the original image to match the |images_| format.
  61   const int x[] =
  62       { 0, insets.left(), image.width() - insets.right(), image.width() };
  63   const int y[] =
  64       { 0, insets.top(), image.height() - insets.bottom(), image.height() };
  65
  66   for (size_t j = 0; j < 3; ++j) {
  67     for (size_t i = 0; i < 3; ++i) {
  68       images_[i + j * 3] = ImageSkiaOperations::ExtractSubset(image,
  69           Rect(x[i], y[j], x[i + 1] - x[i], y[j + 1] - y[j]));
  70     }
  71   }
  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   SkPaint paint;
 102   paint.setAlpha(alpha);
 103
 104   // Get the current transform from the canvas and apply it to the logical
 105   // bounds passed in. This will give us the pixel bounds which can be used
 106   // to draw the images at the correct locations.
 107   // We should not scale the bounds by the canvas->image_scale() as that can be
 108   // different from the real scale in the canvas transform.
 109   SkMatrix matrix = canvas->sk_canvas()->getTotalMatrix();
 110   SkRect scaled_rect;
 111   matrix.mapRect(&scaled_rect, RectToSkRect(bounds));
 112
 113   int scaled_width = gfx::ToCeiledInt(SkScalarToFloat(scaled_rect.width()));
 114   int scaled_height = gfx::ToCeiledInt(SkScalarToFloat(scaled_rect.height()));
 115
 116   // In case the corners and edges don't all have the same width/height, we draw
 117   // the center first, and extend it out in all directions to the edges of the
 118   // images with the smallest widths/heights.  This way there will be no
 119   // unpainted areas, though some corners or edges might overlap the center.
 120   int i0w = ImageWidthInPixels(images_[0], canvas);
 121   int i2w = ImageWidthInPixels(images_[2], canvas);
 122   int i3w = ImageWidthInPixels(images_[3], canvas);
 123   int i5w = ImageWidthInPixels(images_[5], canvas);
 124   int i6w = ImageWidthInPixels(images_[6], canvas);
 125   int i8w = ImageWidthInPixels(images_[8], canvas);
 126
 127   int i4x = std::min(std::min(i0w, i3w), i6w);
 128   int i4w = scaled_width - i4x - std::min(std::min(i2w, i5w), i8w);
 129
 130   int i0h = ImageHeightInPixels(images_[0], canvas);
 131   int i1h = ImageHeightInPixels(images_[1], canvas);
 132   int i2h = ImageHeightInPixels(images_[2], canvas);
 133   int i6h = ImageHeightInPixels(images_[6], canvas);
 134   int i7h = ImageHeightInPixels(images_[7], canvas);
 135   int i8h = ImageHeightInPixels(images_[8], canvas);
 136
 137   int i4y = std::min(std::min(i0h, i1h), i2h);
 138   int i4h = scaled_height - i4y - std::min(std::min(i6h, i7h), i8h);
 139   if (!images_[4].isNull())
 140     Fill(canvas, images_[4], i4x, i4y, i4w, i4h, paint);
 141   canvas->DrawImageIntInPixel(images_[0], 0, 0, i0w, i0h,
 142                               0, 0, i0w, i0h, false, paint);
 143   Fill(canvas, images_[1], i0w, 0, scaled_width - i0w - i2w, i1h, paint);
 144   canvas->DrawImageIntInPixel(images_[2], 0, 0, i2w, i2h, scaled_width - i2w,
 145                               0, i2w, i2h, false, paint);
 146   Fill(canvas, images_[3], 0, i0h, i3w, scaled_height - i0h - i6h, paint);
 147   Fill(canvas, images_[5], scaled_width - i5w, i2h, i5w,
 148        scaled_height - i2h - i8h, paint);
 149   canvas->DrawImageIntInPixel(images_[6], 0, 0, i6w, i6h, 0,
 150                               scaled_height - i6h, i6w, i6h, false, paint);
 151   Fill(canvas, images_[7], i6w, scaled_height - i7h, scaled_width - i6w - i8w,
 152        i7h, paint);
 153   canvas->DrawImageIntInPixel(images_[8], 0, 0, i8w, i8h, scaled_width - i8w,
 154                               scaled_height - i8h, i8w, i8h, false, paint);
 155 }
 156
 157 }  // namespace gfx