allow clients to opt into new didTranslate/didScale

Before
    148.97  	canvas_matrix_4x4	8888
    139.96  	canvas_matrix_3x3	8888
    139.81  	canvas_matrix_2x3	8888
    183.13  	canvas_matrix_scale	8888
    153.72  	canvas_matrix_trans	8888

After
    ...
    114.68  	canvas_matrix_scale	8888
    112.96  	canvas_matrix_trans	8888

Change-Id: I79d20ea6ab6aa9609143c7abf4acaa8ca08dd58f
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/263818
Commit-Queue: Mike Reed <reed@google.com>
Reviewed-by: Mike Reed <reed@google.com>

include/core/SkCanvas.h

@@ -2554,15 +2554,18 @@ protected:
     virtual bool onDoSaveBehind(const SkRect*) { return true; }
     virtual void willRestore() {}
     virtual void didRestore() {}
+
+    virtual void didConcat44(const SkScalar[]) {} // colMajor
     virtual void didConcat(const SkMatrix& ) {}
     virtual void didSetMatrix(const SkMatrix& ) {}
+#ifdef SK_SUPPORT_LEGACY_CANVAS_MATRIX_VIRTUALS
     virtual void didTranslate(SkScalar dx, SkScalar dy) {
-        // TODO: update all subclasses to override this, so we can remove default impl.
         this->didConcat(SkMatrix::MakeTrans(dx, dy));
     }
-    // just pass an array for now, until we decide on the "public" form for the matrix
-    virtual void didConcat44(const SkScalar[]) {}
-    // This is not called by SkCanvas yet. Waiting for subclasses to override it first.
+#else
+    virtual void didTranslate(SkScalar, SkScalar) {}
+#endif
+    // Called if SK_SUPPORT_LEGACY_CANVAS_MATRIX_VIRTUALS is not defined
     virtual void didScale(SkScalar, SkScalar) {}
 
     // NOTE: If you are adding a new onDraw virtual to SkCanvas, PLEASE add an override to

include/private/SkM44.h

@@ -157,6 +157,7 @@ public:
     }
 
     SkM44& preTranslate(SkScalar x, SkScalar y);
+    SkM44& preScale(SkScalar x, SkScalar y);
     SkM44& preConcat(const SkMatrix&);
 
     const SkScalar* asColMajor() const { return fMat; }

src/core/SkCanvas.cpp

@@ -1439,9 +1439,24 @@ void SkCanvas::translate(SkScalar dx, SkScalar dy) {
 }
 
 void SkCanvas::scale(SkScalar sx, SkScalar sy) {
+#ifdef SK_SUPPORT_LEGACY_CANVAS_MATRIX_VIRTUALS
     SkMatrix m;
     m.setScale(sx, sy);
     this->concat(m);
+#else
+    if (sx != 1 || sy != 1) {
+        this->checkForDeferredSave();
+        fMCRec->fMatrix.preScale(sx, sy);
+
+        // shouldn't need to do this (theoretically), as the state shouldn't have changed,
+        // but pre-scaling by a non-finite does change it, so we have to recompute.
+        fIsScaleTranslate = fMCRec->fMatrix.isScaleTranslate();
+
+        FOR_EACH_TOP_DEVICE(device->setGlobalCTM(fMCRec->fMatrix));
+
+        this->didScale(sx, sy);
+    }
+#endif
 }
 
 void SkCanvas::rotate(SkScalar degrees) {

src/core/SkCanvasMatrix.h

@@ -18,6 +18,7 @@ public:
 
     void reset() { fM.setIdentity(); }
     void preTranslate(SkScalar x, SkScalar y) { fM.preTranslate(x, y); }
+    void preScale(SkScalar x, SkScalar y) { fM.preScale(x, y); }
     void preConcat(const SkMatrix& m) { fM.preConcat(m); }
     void preConcat44(const SkScalar m[]) { fM.setConcat(fM, m); }
 

src/core/SkM44.cpp

@@ -97,6 +97,15 @@ SkM44& SkM44::preTranslate(SkScalar x, SkScalar y) {
     return *this;
 }
 
+SkM44& SkM44::preScale(SkScalar x, SkScalar y) {
+    sk4f c0 = sk4f::Load(fMat +  0);
+    sk4f c1 = sk4f::Load(fMat +  4);
+
+    (c0 * x).store(fMat + 0);
+    (c1 * y).store(fMat + 4);
+    return *this;
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 
 /** We always perform the calculation in doubles, to avoid prematurely losing

tests/RecordDrawTest.cpp

@@ -46,7 +46,7 @@ DEF_TEST(RecordDraw_LazySaves, r) {
 
     assert_type<SkRecords::DrawPaint>(r, record, 0);
     assert_type<SkRecords::Save>     (r, record, 1);
-    assert_type<SkRecords::Concat>   (r, record, 2);
+    assert_type<SkRecords::Scale>    (r, record, 2);
     assert_type<SkRecords::Restore>  (r, record, 3);
 
     recorder.save();