Factor code to rotate a canvas about a point.

gm/fontscalerdistortable.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #include "gm.h"
 #include "Resources.h"
 #include "SkFixed.h"
 #include "SkFontDescriptor.h"
 #include "SkFontMgr.h"
 #include "SkTypeface.h"
 
 namespace skiagm {
 
 class FontScalerDistortableGM : public GM {
 public:
     FontScalerDistortableGM() {
         this->setBGColor(0xFFFFFFFF);
     }
 
-    virtual ~FontScalerDistortableGM() { }
-
 protected:
 
     SkString onShortName() override {
         return SkString("fontscalerdistortable");
     }
 
     SkISize onISize() override {
         return SkISize::Make(550, 700);
     }
 
-    static void rotate_about(SkCanvas* canvas, SkScalar degrees, SkScalar px, SkScalar py) {
-        canvas->translate(px, py);
-        canvas->rotate(degrees);
-        canvas->translate(-px, -py);
-    }
-
     void onDraw(SkCanvas* canvas) override {
         SkPaint paint;
         paint.setAntiAlias(true);
         paint.setLCDRenderText(true);
         SkAutoTUnref<SkFontMgr> fontMgr(SkFontMgr::RefDefault());
 
         SkAutoTDelete<SkStreamAsset> distortable(GetResourceAsStream("/fonts/Distortable.ttf"));
         if (!distortable) {
             return;
         }
         const char* text = "abc";
         const size_t textLen = strlen(text);
 
         for (int j = 0; j < 2; ++j) {
             for (int i = 0; i < 5; ++i) {
                 SkScalar x = SkIntToScalar(10);
                 SkScalar y = SkIntToScalar(20);
 
                 SkFourByteTag tag = SkSetFourByteTag('w','g','h','t');
                 SkScalar styleValue = SkDoubleToScalar(0.5 + (5*j + i) * ((2.0 - 0.5) / (2 * 5)));
                 SkFontMgr::FontParameters::Axis axes[] = { { tag, styleValue } };
                 paint.setTypeface(sk_sp<SkTypeface>(fontMgr->createFromStream(
                         distortable->duplicate(), SkFontMgr::FontParameters().setAxes(axes, 1))));
 
                 SkAutoCanvasRestore acr(canvas, true);
                 canvas->translate(SkIntToScalar(30 + i * 100), SkIntToScalar(20));
-                rotate_about(canvas, SkIntToScalar(i * 5), x, y * 10);
+                canvas->rotate(SkIntToScalar(i * 5), x, y * 10);
 
                 {
                     SkPaint p;
                     p.setAntiAlias(true);
                     SkRect r;
                     r.set(x - SkIntToScalar(3), SkIntToScalar(15),
                           x - SkIntToScalar(1), SkIntToScalar(280));
                     canvas->drawRect(r, p);
                 }
 
@@ skipping 11 matching lines @@
 private:
     typedef GM INHERITED;
 };
 
 //////////////////////////////////////////////////////////////////////////////
 
 static GM* MyFactory(void*) { return new FontScalerDistortableGM; }
 static GMRegistry reg(MyFactory);
 
 }