Fix cases of variable shadowing in /gm/.

If we manage to fix all the existing cases of variable shadowing, we
could enable -Wshadow.

Change-Id: I905459bf0bbaa205da7dc59e1910e345bed2af51
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/438538
Commit-Queue: John Stiles <johnstiles@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
diff --git a/gm/bleed.cpp b/gm/bleed.cpp
index 8125319..1c0d6e0 100644
--- a/gm/bleed.cpp
+++ b/gm/bleed.cpp
@@ -237,9 +237,8 @@
         // Align the next set with the middle of the previous in y, translated to the right in x.
         SkPoint corners[] = {{0, 0}, {0, kBottom}, {kWidth, kBottom}, {kWidth, 0}};
         matrices.back().mapPoints(corners, 4);
-        SkScalar y = (corners[0].fY + corners[1].fY + corners[2].fY + corners[3].fY) / 4;
-        SkScalar x = std::max({corners[0].fX, corners[1].fX, corners[2].fX, corners[3].fX});
-        m.setTranslate(x, y);
+        m.setTranslate(std::max({corners[0].fX, corners[1].fX, corners[2].fX, corners[3].fX}),
+                       (corners[0].fY + corners[1].fY + corners[2].fY + corners[3].fY) / 4);
         m.preScale(0.2f, 0.2f);
         matrices.push_back(m);
 
diff --git a/gm/blurrect.cpp b/gm/blurrect.cpp
index 0e0c691..0f15c49 100644
--- a/gm/blurrect.cpp
+++ b/gm/blurrect.cpp
@@ -373,11 +373,11 @@
                     // the single x-pass value from our precomputed row.
                     float tdiff = numSubpixels * pad - (y * numSubpixels + ys + 0.5f);
                     float bdiff = tdiff + h;
-                    auto w = def_integral_approx(tdiff, bdiff);
+                    auto integral = def_integral_approx(tdiff, bdiff);
                     for (int x = 0; x < maskW; ++x) {
                         for (int xs = 0; xs < numSubpixels; ++xs) {
                             int rowIdx = x * numSubpixels + xs;
-                            accums[x] += w * row[rowIdx];
+                            accums[x] += integral * row[rowIdx];
                         }
                     }
                 }
diff --git a/gm/drawbitmaprect.cpp b/gm/drawbitmaprect.cpp
index e7f4f21..d160274 100644
--- a/gm/drawbitmaprect.cpp
+++ b/gm/drawbitmaprect.cpp
@@ -184,9 +184,10 @@
 
         const int kPadX = 30;
         const int kPadY = 40;
-        SkPaint paint;
-        paint.setAlphaf(0.125f);
-        canvas->drawImageRect(fImage, SkRect::MakeIWH(gSize, gSize), SkSamplingOptions(), &paint);
+        SkPaint alphaPaint;
+        alphaPaint.setAlphaf(0.125f);
+        canvas->drawImageRect(fImage, SkRect::MakeIWH(gSize, gSize), SkSamplingOptions(),
+                              &alphaPaint);
         canvas->translate(SK_Scalar1 * kPadX / 2,
                           SK_Scalar1 * kPadY / 2);
         SkPaint blackPaint;
@@ -237,16 +238,16 @@
             // test the following code path:
             // SkGpuDevice::drawPath() -> SkGpuDevice::drawWithMaskFilter()
             SkIRect srcRect;
-            SkPaint paint;
+            SkPaint maskPaint;
             SkBitmap bm = make_chessbm(5, 5);
 
             srcRect.setXYWH(1, 1, 3, 3);
-            paint.setMaskFilter(SkMaskFilter::MakeBlur(
+            maskPaint.setMaskFilter(SkMaskFilter::MakeBlur(
                 kNormal_SkBlurStyle,
                 SkBlurMask::ConvertRadiusToSigma(SkIntToScalar(5))));
 
             fProc(canvas, bm.asImage().get(), bm, srcRect, dstRect,
-                  SkSamplingOptions(SkFilterMode::kLinear), &paint);
+                  SkSamplingOptions(SkFilterMode::kLinear), &maskPaint);
         }
     }
 
diff --git a/gm/fontmgr.cpp b/gm/fontmgr.cpp
index 92d108e..694e6a5 100644
--- a/gm/fontmgr.cpp
+++ b/gm/fontmgr.cpp
@@ -311,7 +311,7 @@
                                    SkTextEncoding::kGlyphID, 0, 0, font, glyphPaint);
 
             if (labelBounds) {
-                SkAutoCanvasRestore acr(canvas, true);
+                SkAutoCanvasRestore acr2(canvas, true);
                 canvas->translate(glyphToDraw.location.fX, glyphToDraw.location.fY);
                 canvas->rotate(glyphToDraw.rotation);
                 SkString glyphStr;
diff --git a/gm/gradients.cpp b/gm/gradients.cpp
index c5a3e07..50d88e4 100644
--- a/gm/gradients.cpp
+++ b/gm/gradients.cpp
@@ -601,8 +601,8 @@
     void onOnceBeforeDraw() override {
         const SkPoint center = { 0, 0 };
         const SkScalar kRadius = 3000;
-        const SkColor gColors[] = { 0xFFFFFFFF, 0xFF000000 };
-        fShader = SkGradientShader::MakeRadial(center, kRadius, gColors, nullptr, 2,
+        const SkColor kColors[] = { 0xFFFFFFFF, 0xFF000000 };
+        fShader = SkGradientShader::MakeRadial(center, kRadius, kColors, nullptr, 2,
                                                SkTileMode::kClamp);
     }
 
diff --git a/gm/imagefiltersbase.cpp b/gm/imagefiltersbase.cpp
index 1bbc9a2..ec02999 100644
--- a/gm/imagefiltersbase.cpp
+++ b/gm/imagefiltersbase.cpp
@@ -318,8 +318,6 @@
     virtual void installFilter(SkPaint* paint) = 0;
 
     void onDraw(SkCanvas* canvas) override {
-        SkPaint paint;
-
         canvas->translate(20, 40);
 
         for (int doSaveLayer = 0; doSaveLayer <= 1; ++doSaveLayer) {
diff --git a/gm/ovals.cpp b/gm/ovals.cpp
index f6d9669..cae0cec 100644
--- a/gm/ovals.cpp
+++ b/gm/ovals.cpp
@@ -146,7 +146,7 @@
     void onDraw(SkCanvas* canvas) override {
         SkRandom rand(1);
         canvas->translate(20 * SK_Scalar1, 20 * SK_Scalar1);
-        SkRect oval = SkRect::MakeLTRB(-20, -30, 20, 30);
+        const SkRect kOval = SkRect::MakeLTRB(-20, -30, 20, 30);
 
         const SkScalar kXStart = 60.0f;
         const SkScalar kYStart = 80.0f;
@@ -175,8 +175,8 @@
                 SkColor color = genColor(&rand);
                 fPaints[i].setColor(color);
 
-                canvas->drawRect(oval, rectPaint);
-                canvas->drawOval(oval, fPaints[i]);
+                canvas->drawRect(kOval, rectPaint);
+                canvas->drawOval(kOval, fPaints[i]);
 
                 canvas->restore();
 
@@ -268,8 +268,8 @@
             fPaints[i].setColor(color);
             fPaints[i].setShader(shader);
 
-            canvas->drawRect(oval, rectPaint);
-            canvas->drawOval(oval, fPaints[i]);
+            canvas->drawRect(kOval, rectPaint);
+            canvas->drawOval(kOval, fPaints[i]);
 
             fPaints[i].setShader(nullptr);
 
diff --git a/gm/polygonoffset.cpp b/gm/polygonoffset.cpp
index c5470dc..96ccfb5 100644
--- a/gm/polygonoffset.cpp
+++ b/gm/polygonoffset.cpp
@@ -507,10 +507,9 @@
         }
     }
     // Draw a single polygon with insets and potentially outsets
-    void drawPolygon(SkCanvas* canvas, int index, SkPoint* offset) {
+    void drawPolygon(SkCanvas* canvas, int index, SkPoint* position) {
 
         SkPoint center;
-        SkRect bounds;
         {
             std::unique_ptr<SkPoint[]> data(nullptr);
             int numPts;
@@ -519,16 +518,17 @@
             } else {
                 GetSimplePolygon(index, SkPathDirection::kCW, &data, &numPts);
             }
+            SkRect bounds;
             bounds.setBounds(data.get(), numPts);
             if (!fConvexOnly) {
                 bounds.outset(kMaxOutset, kMaxOutset);
             }
-            if (offset->fX + bounds.width() > kGMWidth) {
-                offset->fX = 0;
-                offset->fY += kMaxPathHeight;
+            if (position->fX + bounds.width() > kGMWidth) {
+                position->fX = 0;
+                position->fY += kMaxPathHeight;
             }
-            center = { offset->fX + SkScalarHalf(bounds.width()), offset->fY };
-            offset->fX += bounds.width();
+            center = { position->fX + SkScalarHalf(bounds.width()), position->fY };
+            position->fX += bounds.width();
         }
 
         const SkPathDirection dirs[2] = { SkPathDirection::kCW, SkPathDirection::kCCW };
@@ -581,8 +581,8 @@
             if (result) {
                 SkPath path;
                 path.moveTo(offsetPoly[0]);
-                for (int i = 1; i < offsetPoly.count(); ++i) {
-                    path.lineTo(offsetPoly[i]);
+                for (int j = 1; j < offsetPoly.count(); ++j) {
+                    path.lineTo(offsetPoly[j]);
                 }
                 path.close();
 
diff --git a/gm/recordopts.cpp b/gm/recordopts.cpp
index 5a873e7..bfee2ee 100644
--- a/gm/recordopts.cpp
+++ b/gm/recordopts.cpp
@@ -83,11 +83,11 @@
     bitmap.eraseColor(shapeColor);
     {
         // Make the bitmap non-uniform color, so that it can not be optimized as uniform drawRect.
-        SkCanvas canvas(bitmap);
+        SkCanvas bitmapCanvas(bitmap);
         SkPaint p;
         p.setColor(SK_ColorWHITE);
         SkASSERT(shapeColor != SK_ColorWHITE);
-        canvas.drawRect(SkRect::MakeWH(SkIntToScalar(7), SkIntToScalar(7)), p);
+        bitmapCanvas.drawRect(SkRect::MakeWH(SkIntToScalar(7), SkIntToScalar(7)), p);
     }
 
     SkRect targetRect(SkRect::MakeWH(SkIntToScalar(kTestRectSize), SkIntToScalar(kTestRectSize)));
@@ -109,11 +109,11 @@
     sk_sp<SkPicture> shape;
     {
         SkPictureRecorder recorder;
-        SkCanvas* canvas = recorder.beginRecording(SkIntToScalar(kTestRectSize + 2),
-                                                   SkIntToScalar(kTestRectSize + 2));
+        SkCanvas* recordCanvas = recorder.beginRecording(SkIntToScalar(kTestRectSize + 2),
+                                                         SkIntToScalar(kTestRectSize + 2));
         SkPaint shapePaint;
         shapePaint.setColor(shapeColor);
-        canvas->drawRect(targetRect, shapePaint);
+        recordCanvas->drawRect(targetRect, shapePaint);
         shape = recorder.finishRecordingAsPicture();
     }
 
diff --git a/gm/rectangletexture.cpp b/gm/rectangletexture.cpp
index f4601cd..b0e8761 100644
--- a/gm/rectangletexture.cpp
+++ b/gm/rectangletexture.cpp
@@ -163,9 +163,9 @@
             auto img = fGradImgs[i];
             int w = img->width();
             int h = img->height();
-            for (auto s : kScales) {
+            for (auto scale : kScales) {
                 canvas->save();
-                canvas->scale(s, s);
+                canvas->scale(scale, scale);
                 for (auto s : kSamplings) {
                     // drawImage
                     canvas->drawImage(img, 0, 0, s);
@@ -193,7 +193,7 @@
                     canvas->translate(.5f*w + kPad, 0);
                 }
                 canvas->restore();
-                canvas->translate(0, kPad + 1.5f*h*s);
+                canvas->translate(0, kPad + 1.5f*h*scale);
             }
         }
 
diff --git a/gm/roundrects.cpp b/gm/roundrects.cpp
index d05de86..e216bc4 100644
--- a/gm/roundrects.cpp
+++ b/gm/roundrects.cpp
@@ -147,9 +147,9 @@
     void onDraw(SkCanvas* canvas) override {
         SkRandom rand(1);
         canvas->translate(20 * SK_Scalar1, 20 * SK_Scalar1);
-        const SkRect rect = SkRect::MakeLTRB(-20, -30, 20, 30);
-        SkRRect circleRect;
-        circleRect.setRectXY(rect, 5, 5);
+        const SkRect kRect = SkRect::MakeLTRB(-20, -30, 20, 30);
+        SkRRect circleRRect;
+        circleRRect.setRectXY(kRect, 5, 5);
 
         const SkScalar kXStart = 60.0f;
         const SkScalar kYStart = 80.0f;
@@ -178,8 +178,8 @@
                 SkColor color = gen_color(&rand);
                 fPaints[i].setColor(color);
 
-                canvas->drawRect(rect, rectPaint);
-                canvas->drawRRect(circleRect, fPaints[i]);
+                canvas->drawRect(kRect, rectPaint);
+                canvas->drawRRect(circleRRect, fPaints[i]);
 
                 canvas->restore();
 
@@ -283,8 +283,8 @@
             fPaints[i].setColor(color);
             fPaints[i].setShader(shader);
 
-            canvas->drawRect(rect, rectPaint);
-            canvas->drawRRect(circleRect, fPaints[i]);
+            canvas->drawRect(kRect, rectPaint);
+            canvas->drawRRect(circleRRect, fPaints[i]);
 
             fPaints[i].setShader(nullptr);
 
@@ -306,7 +306,7 @@
 
             for (int i = 0; i < 4; ++i) {
                 SkRRect circleRect;
-                circleRect.setRectXY(rect, radii[i][0], radii[i][1]);
+                circleRect.setRectXY(kRect, radii[i][0], radii[i][1]);
 
                 canvas->save();
                 // position the roundrect, and make it at off-integer coords.
diff --git a/gm/shadowutils.cpp b/gm/shadowutils.cpp
index 214027c..5364c08 100644
--- a/gm/shadowutils.cpp
+++ b/gm/shadowutils.cpp
@@ -91,9 +91,7 @@
     SkScalar dy = 0;
     SkTDArray<SkMatrix> matrices;
     matrices.push()->reset();
-    SkMatrix* m = matrices.push();
-    m->setRotate(33.f, 25.f, 25.f);
-    m->postScale(1.2f, 0.8f, 25.f, 25.f);
+    matrices.push()->setRotate(33.f, 25.f, 25.f).postScale(1.2f, 0.8f, 25.f, 25.f);
     for (auto& m : matrices) {
         for (int flags : { kNone_ShadowFlag, kTransparentOccluder_ShadowFlag }) {
             int pathCounter = 0;
diff --git a/gm/sharedcorners.cpp b/gm/sharedcorners.cpp
index aadf896..cc00432 100644
--- a/gm/sharedcorners.cpp
+++ b/gm/sharedcorners.cpp
@@ -149,7 +149,7 @@
 
         for (SkPoint jitter : kJitters) {
             {
-                SkAutoCanvasRestore acr(canvas, true);
+                SkAutoCanvasRestore acr2(canvas, true);
                 canvas->translate(jitter.x(), jitter.y());
                 canvas->drawPath(path, fFillPaint);
             }