Add function to get both min and max scale factors from matrix

tests/MatrixTest.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkMath.h"
 #include "SkMatrix.h"
 #include "SkMatrixUtils.h"
@@ skipping 102 matching lines @@
     REPORTER_ASSERT(reporter, size1 == size3);
     REPORTER_ASSERT(reporter, are_equal(reporter, m, m2));
 
     char buffer2[kBufferSize];
     size3 = m2.writeToMemory(buffer2);
     REPORTER_ASSERT(reporter, size1 == size3);
     REPORTER_ASSERT(reporter, memcmp(buffer, buffer2, size1) == 0);
 }
 
 static void test_matrix_min_max_scale(skiatest::Reporter* reporter) {
+    SkScalar scales[2];
+    bool success;
+
     SkMatrix identity;
     identity.reset();
     REPORTER_ASSERT(reporter, SK_Scalar1 == identity.getMinScale());
     REPORTER_ASSERT(reporter, SK_Scalar1 == identity.getMaxScale());
+    success = identity.getMinMaxScales(scales);
+    REPORTER_ASSERT(reporter, success && SK_Scalar1 == scales[0] && SK_Scalar1 == scales[1]);
 
     SkMatrix scale;
     scale.setScale(SK_Scalar1 * 2, SK_Scalar1 * 4);
     REPORTER_ASSERT(reporter, SK_Scalar1 * 2 == scale.getMinScale());
     REPORTER_ASSERT(reporter, SK_Scalar1 * 4 == scale.getMaxScale());
+    success = scale.getMinMaxScales(scales);
+    REPORTER_ASSERT(reporter, success && SK_Scalar1 * 2 == scales[0] && SK_Scalar1 * 4 == scales[1]);
 
     SkMatrix rot90Scale;
     rot90Scale.setRotate(90 * SK_Scalar1);
     rot90Scale.postScale(SK_Scalar1 / 4, SK_Scalar1 / 2);
     REPORTER_ASSERT(reporter, SK_Scalar1 / 4 == rot90Scale.getMinScale());
     REPORTER_ASSERT(reporter, SK_Scalar1 / 2 == rot90Scale.getMaxScale());
+    success = rot90Scale.getMinMaxScales(scales);
+    REPORTER_ASSERT(reporter, success && SK_Scalar1 / 4  == scales[0] && SK_Scalar1 / 2 == scales[1]);
 
     SkMatrix rotate;
     rotate.setRotate(128 * SK_Scalar1);
-    REPORTER_ASSERT(reporter, SkScalarNearlyEqual(SK_Scalar1, rotate.getMinScale() ,SK_ScalarNearlyZero));
+    REPORTER_ASSERT(reporter, SkScalarNearlyEqual(SK_Scalar1, rotate.getMinScale(), SK_ScalarNearlyZero));
     REPORTER_ASSERT(reporter, SkScalarNearlyEqual(SK_Scalar1, rotate.getMaxScale(), SK_ScalarNearlyZero));
+    success = rotate.getMinMaxScales(scales);
+    REPORTER_ASSERT(reporter, success);
+    REPORTER_ASSERT(reporter, SkScalarNearlyEqual(SK_Scalar1, scales[0], SK_ScalarNearlyZero));
+    REPORTER_ASSERT(reporter, SkScalarNearlyEqual(SK_Scalar1, scales[1], SK_ScalarNearlyZero));
 
     SkMatrix translate;
     translate.setTranslate(10 * SK_Scalar1, -5 * SK_Scalar1);
     REPORTER_ASSERT(reporter, SK_Scalar1 == translate.getMinScale());
     REPORTER_ASSERT(reporter, SK_Scalar1 == translate.getMaxScale());
+    success = translate.getMinMaxScales(scales);
+    REPORTER_ASSERT(reporter, success && SK_Scalar1 == scales[0] && SK_Scalar1 == scales[1]);
 
     SkMatrix perspX;
     perspX.reset();
     perspX.setPerspX(SkScalarToPersp(SK_Scalar1 / 1000));
     REPORTER_ASSERT(reporter, -SK_Scalar1 == perspX.getMinScale());
     REPORTER_ASSERT(reporter, -SK_Scalar1 == perspX.getMaxScale());
+    // Verify that getMinMaxScales() doesn't update the scales array on failure.
+    scales[0] = -5;
+    scales[1] = -5;
+    success = perspX.getMinMaxScales(scales);
+    REPORTER_ASSERT(reporter, !success && -5 * SK_Scalar1 == scales[0] && -5 * SK_Scalar1  == scales[1]);
 
     SkMatrix perspY;
     perspY.reset();
     perspY.setPerspY(SkScalarToPersp(-SK_Scalar1 / 500));
     REPORTER_ASSERT(reporter, -SK_Scalar1 == perspY.getMinScale());
     REPORTER_ASSERT(reporter, -SK_Scalar1 == perspY.getMaxScale());
+    scales[0] = -5;
+    scales[1] = -5;
+    success = perspY.getMinMaxScales(scales);
+    REPORTER_ASSERT(reporter, !success && -5 * SK_Scalar1 == scales[0] && -5 * SK_Scalar1  == scales[1]);
 
     SkMatrix baseMats[] = {scale, rot90Scale, rotate,
                            translate, perspX, perspY};
     SkMatrix mats[2*SK_ARRAY_COUNT(baseMats)];
     for (size_t i = 0; i < SK_ARRAY_COUNT(baseMats); ++i) {
         mats[i] = baseMats[i];
         bool invertable = mats[i].invert(&mats[i + SK_ARRAY_COUNT(baseMats)]);
         REPORTER_ASSERT(reporter, invertable);
     }
     SkRandom rand;
     for (int m = 0; m < 1000; ++m) {
         SkMatrix mat;
         mat.reset();
         for (int i = 0; i < 4; ++i) {
             int x = rand.nextU() % SK_ARRAY_COUNT(mats);
             mat.postConcat(mats[x]);
         }
 
         SkScalar minScale = mat.getMinScale();
         SkScalar maxScale = mat.getMaxScale();
         REPORTER_ASSERT(reporter, (minScale < 0) == (maxScale < 0));
         REPORTER_ASSERT(reporter, (maxScale < 0) == mat.hasPerspective());
 
+        SkScalar scales[2];
+        bool success = mat.getMinMaxScales(scales);
+        REPORTER_ASSERT(reporter, success == !mat.hasPerspective());
+        REPORTER_ASSERT(reporter, !success || (scales[0] == minScale && scales[1] == maxScale));
+
         if (mat.hasPerspective()) {
             m -= 1; // try another non-persp matrix
             continue;
         }
 
         // test a bunch of vectors. All should be scaled by between minScale and maxScale
         // (modulo some error) and we should find a vector that is scaled by almost each.
         static const SkScalar gVectorScaleTol = (105 * SK_Scalar1) / 100;
         static const SkScalar gCloseScaleTol = (97 * SK_Scalar1) / 100;
         SkScalar max = 0, min = SK_ScalarMax;
@@ skipping 598 matching lines @@
     a.setTranslate(10, 20);
 
     SkMatrix b;
     b.setScale(3, 5);
 
     SkMatrix expected;
     expected.setConcat(a,b);
 
     REPORTER_ASSERT(r, expected == SkMatrix::Concat(a, b));
 }