Support horizontal/vertical only images in NineImagePainter.

This will be used in https://codereview.chromium.org/798163003/

BUG=432500

Review URL: https://codereview.chromium.org/806433002

Cr-Commit-Position: refs/heads/master@{#308440}

ui/base/nine_image_painter_factory.h

@@ -23,6 +23,17 @@
       x ## _LEFT, EMPTY_IMAGE, x ## _RIGHT, \
       x ## _BOTTOM_LEFT, x ## _BOTTOM, x ## _BOTTOM_RIGHT, }
 
+// A macro to define arrays of IDR constants used with CreateImageGridPainter
+// where it can only be streched horizontally.
+#define IMAGE_GRID_HORIZONTAL(x) { x ## _LEFT, x ## _CENTER, x ## _RIGHT, \
+      EMPTY_IMAGE, EMPTY_IMAGE, EMPTY_IMAGE, \
+      EMPTY_IMAGE, EMPTY_IMAGE, EMPTY_IMAGE}
+
+// A macro to define arrays of IDR constants used with CreateImageGridPainter
+// where it can only be streched vertically.
+#define IMAGE_GRID_VERTICAL(x) { x ## _TOP, EMPTY_IMAGE, EMPTY_IMAGE, \
+        x ## _CENTER, EMPTY_IMAGE, EMPTY_IMAGE, \
+        x ## _BOTTOM, EMPTY_IMAGE, EMPTY_IMAGE}
 
 namespace gfx {
 class NineImagePainter;

ui/gfx/nine_image_painter.cc

@@ -25,10 +25,14 @@ namespace {
 // The following functions width and height of the image in pixels for the
 // scale factor in the Canvas.
 int ImageWidthInPixels(const ImageSkia& i, Canvas* c) {
+  if (i.isNull())
+    return 0;
   return i.GetRepresentation(c->image_scale()).pixel_width();
 }
 
 int ImageHeightInPixels(const ImageSkia& i, Canvas* c) {
+  if (i.isNull())
+    return 0;
   return i.GetRepresentation(c->image_scale()).pixel_height();
 }
 
@@ -40,6 +44,8 @@ void Fill(Canvas* c,
           int w,
           int h,
           const SkPaint& paint) {
+  if (i.isNull())
+    return;
   c->DrawImageIntInPixel(i, 0, 0, ImageWidthInPixels(i, c),
                          ImageHeightInPixels(i, c), x, y, w, h, false, paint);
 }
@@ -146,22 +152,27 @@ void NineImagePainter::Paint(Canvas* canvas,
   SkPaint paint;
   paint.setAlpha(alpha);
 
-  if (!images_[4].isNull())
-    Fill(canvas, images_[4], i4x, i4y, i4w, i4h, paint);
   canvas->DrawImageIntInPixel(images_[0], 0, 0, i0w, i0h,
                               0, 0, i0w, i0h, false, paint);
+
   Fill(canvas, images_[1], i0w, 0, width_in_pixels - i0w - i2w, i1h, paint);
-  canvas->DrawImageIntInPixel(images_[2], 0, 0, i2w, i2h, width_in_pixels - i2w,
-                              0, i2w, i2h, false, paint);
+
+  Fill(canvas, images_[2], width_in_pixels - i2w, 0, i2w, i2h, paint);
+
   Fill(canvas, images_[3], 0, i0h, i3w, height_in_pixels - i0h - i6h, paint);
+
+  Fill(canvas, images_[4], i4x, i4y, i4w, i4h, paint);
+
   Fill(canvas, images_[5], width_in_pixels - i5w, i2h, i5w,
        height_in_pixels - i2h - i8h, paint);
-  canvas->DrawImageIntInPixel(images_[6], 0, 0, i6w, i6h, 0,
-                              height_in_pixels - i6h, i6w, i6h, false, paint);
+
+  Fill(canvas, images_[6], 0, height_in_pixels - i6h, i6w, i6h, paint);
+
   Fill(canvas, images_[7], i6w, height_in_pixels - i7h,
        width_in_pixels - i6w - i8w, i7h, paint);
-  canvas->DrawImageIntInPixel(images_[8], 0, 0, i8w, i8h, width_in_pixels - i8w,
-                              height_in_pixels - i8h, i8w, i8h, false, paint);
+
+  Fill(canvas, images_[8], width_in_pixels - i8w, height_in_pixels - i8h, i8w,
+       i8h, paint);
 }
 
 }  // namespace gfx