Bug 20667 – Animation of -webkit-transform matrix() function should not do linear interpolation

• Component: CSS
• Status: RESOLVED FIXED

[Chris Marrin]

Currently, the 6 components of the matrix() function are linearly interpolated. This causes simple rotations to grow and shrink as they animate and other problems. We should do decomposition of the matrix into scale, rotation, skew and translation components, then linearly interpolated, then recomposed into an affine transform.

[Chris Marrin]

Created attachment 23195 [details]
Patch to fix bug

[Sam Weinig]

Comment on attachment 23195 [details]
Patch to fix bug

Just style nits.

+    double sx, sy;
+    double angle;
We don't usually pre declare variables.

+    /* Compute scaling factors. */
We tend to use C++ style comments.  This issue is in a few 

+    sx = sqrt (m.a() * m.a() + m.b() * m.b());
+    sy = sqrt (m.c() * m.c() + m.d() * m.d());
Space after sqrt.

+    angle = atan2 (m.b(), m.a());
Space after atan2.

+    int i;
No need to pre declare this.

+        srA[2] += srA[2] < 0 ? M_PI : -M_PI;
+    }
+
+    // Don't rotate the long way around.
+    srA[2] = fmod(srA[2], 2.0 * M_PI);
+    srB[2] = fmod(srB[2], 2.0 * M_PI);
+
+    if (fabs (srA[2] - srB[2]) > M_PI) {
+        if (srA[2] > srB[2])
+            srA[2] -= M_PI * 2.0;
+        else
+            srB[2] -= M_PI * 2.0;
+    }
We use piDouble/piFloat instead of M_PI

[Chris Marrin]

Created attachment 23206 [details]
New patch fixing nits

[Sam Weinig]

Comment on attachment 23206 [details]
New patch fixing nits

Still one space after function name.
+    if (fabs (srA[2] - srB[2]) > piDouble) {

Please fix that before landing. r=me

[Dean Jackson]

	M	LayoutTests/ChangeLog
	A	LayoutTests/animations/matrix-anim-expected.txt
	A	LayoutTests/animations/matrix-anim.html
	M	WebCore/ChangeLog
	M	WebCore/platform/graphics/AffineTransform.cpp
	M	WebCore/platform/graphics/AffineTransform.h
	M	WebCore/rendering/style/RenderStyle.cpp
Committed r36274

[Dean Jackson]

forgot to fix sam's comment.

	M	WebCore/ChangeLog
	M	WebCore/platform/graphics/AffineTransform.cpp
Committed r36275