Move work from ctor to onOnceBeforeDraw in ShowMipLevel GMs

gm/showmiplevels.cpp

 /*
  * Copyright 2016 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"
@@ skipping 87 matching lines @@
             for (int x = 0; x < bm.width(); ++x) {
                 SkPMColor c = *bm.getAddr32(x, y);
                 unsigned r = gamma(SkGetPackedR32(c));
                 unsigned g = gamma(SkGetPackedG32(c));
                 unsigned b = gamma(SkGetPackedB32(c));
                 *bm.getAddr32(x, y) = SkPackARGB32(0xFF, r, g, b);
             }
         }
     }
 
-    ShowMipLevels(int N) : fN(N) {
-        fBM[0] = sk_tool_utils::create_checkerboard_bitmap(N, N, SK_ColorBLACK, SK_ColorWHITE, 2);
-        fBM[1] = make_bitmap(N, N);
-        fBM[2] = make_bitmap2(N, N);
-        fBM[3] = make_bitmap3(N, N);
-    }
+    ShowMipLevels(int N) : fN(N) { }
 
 protected:
 
     SkString onShortName() override {
         SkString str;
         str.printf("showmiplevels_%d", fN);
         return str;
     }
 
     SkISize onISize() override {
@@ skipping 67 matching lines @@
         for (auto method : methods) {
             canvas->translate(orig.width()/2 + 8.0f, 0);
             drawLevels(canvas, orig, [basePM, method](const SkPixmap& prev, const SkPixmap& curr) {
                 SkBitmap bm;
                 SkBitmapScaler::Resize(&bm, prev, method, curr.width(), curr.height());
                 return bm;
             });
         }
     }
 
+    void onOnceBeforeDraw() override {
+        fBM[0] = sk_tool_utils::create_checkerboard_bitmap(fN, fN, SK_ColorBLACK, SK_ColorWHITE, 2);
+        fBM[1] = make_bitmap(fN, fN);
+        fBM[2] = make_bitmap2(fN, fN);
+        fBM[3] = make_bitmap3(fN, fN);
+    }
+
     void onDraw(SkCanvas* canvas) override {
         canvas->translate(4, 4);
         for (const auto& bm : fBM) {
             this->drawSet(canvas, bm);
             canvas->translate(0, bm.height() * 0.85f);
         }
     }
 
 private:
     typedef skiagm::GM INHERITED;
 };
 DEF_GM( return new ShowMipLevels(255); )
 DEF_GM( return new ShowMipLevels(256); )
 
 ///////////////////////////////////////////////////////////////////////////////////////////////////
 
 /**
  *  Show mip levels that were built, for all supported colortypes
  */
 class ShowMipLevels2 : public skiagm::GM {
     const int fW, fH;
     SkBitmap  fBM[4];
 
 public:
-    ShowMipLevels2(int w, int h) : fW(w), fH(h) {
-        fBM[0] = sk_tool_utils::create_checkerboard_bitmap(w, h, SHOW_MIP_COLOR, SK_ColorWHITE, 2);
-        fBM[1] = make_bitmap(w, h);
-        fBM[2] = make_bitmap2(w, h);
-        fBM[3] = make_bitmap3(w, h);
-    }
+    ShowMipLevels2(int w, int h) : fW(w), fH(h) { }
 
 protected:
 
     SkString onShortName() override {
         SkString str;
         str.printf("showmiplevels2_%dx%d", fW, fH);
         return str;
     }
 
     SkISize onISize() override {
@@ skipping 44 matching lines @@
         SkAutoCanvasRestore acr(canvas, true);
 
         for (auto ctype : ctypes) {
             SkBitmap bm;
             orig.copyTo(&bm, ctype);
             drawLevels(canvas, bm);
             canvas->translate(orig.width()/2 + 8.0f, 0);
         }
     }
 
+    void onOnceBeforeDraw() override {
+        fBM[0] = sk_tool_utils::create_checkerboard_bitmap(fW, fH,
+                                                           SHOW_MIP_COLOR, SK_ColorWHITE, 2);
+        fBM[1] = make_bitmap(fW, fH);
+        fBM[2] = make_bitmap2(fW, fH);
+        fBM[3] = make_bitmap3(fW, fH);
+    }
+
     void onDraw(SkCanvas* canvas) override {
         canvas->translate(4, 4);
         for (const auto& bm : fBM) {
             this->drawSet(canvas, bm);
             // round so we always produce an integral translate, so the GOLD tool won't show
             // unimportant diffs if this is drawn on a GPU with different rounding rules
             // since we draw the bitmaps using nearest-neighbor
             canvas->translate(0, SkScalarRoundToScalar(bm.height() * 0.85f));
         }
     }
 
 private:
     typedef skiagm::GM INHERITED;
 };
 DEF_GM( return new ShowMipLevels2(255, 255); )
 DEF_GM( return new ShowMipLevels2(256, 255); )
 DEF_GM( return new ShowMipLevels2(255, 256); )
 DEF_GM( return new ShowMipLevels2(256, 256); )