Added check for invalid transform.
Test: A transform whose matrix is not invertible.
Change-Id: I6b0b5b9a1c890c8a8694f17a4fbe52a2e875b51a
Merged-In: I6b0b5b9a1c890c8a8694f17a4fbe52a2e875b51a
diff --git a/tools/winscope/src/transform_sf.js b/tools/winscope/src/transform_sf.js
index e125ccf..2e1cf6a 100644
--- a/tools/winscope/src/transform_sf.js
+++ b/tools/winscope/src/transform_sf.js
@@ -122,6 +122,25 @@
(rect.left - rect.right === 0 || rect.top - rect.bottom === 0);
}
+ function is_transform_invalid(transform) {
+ return !transform || (transform.dsdx * transform.dtdy ===
+ transform.dtdx * transform.dsdy); //determinant of transform
+ /**
+ * The transformation matrix is defined as the product of:
+ * | cos(a) -sin(a) | \/ | X 0 |
+ * | sin(a) cos(a) | /\ | 0 Y |
+ *
+ * where a is a rotation angle, and X and Y are scaling factors.
+ * A transformation matrix is invalid when either X or Y is zero,
+ * as a rotation matrix is valid for any angle. When either X or Y
+ * is 0, then the scaling matrix is not invertible, which makes the
+ * transformation matrix not invertible as well. A 2D matrix with
+ * components | A B | is uninvertible if and only if AD - BC = 0.
+ * | C D |
+ * This check is included above.
+ */
+ }
+
/**
* Checks if the layer is visible on screen according to its type,
* active buffer content, alpha and visible regions.
@@ -187,8 +206,8 @@
if (is_rect_empty_and_valid(layer.crop)) {
reasons.push('Crop is zero');
}
- if (!layer.transform || (layer.type === 'BufferLayer'
- && !layer.bufferTransform)) {
+ if (is_transform_invalid(layer.transform) || (layer.type === 'BufferLayer'
+ && is_transform_invalid(layer.bufferTransform))) {
reasons.push('Transform is invalid');
}
return reasons.join();
