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Bug 979658 part 3 - Make LayerTransactionParent::RecvGetTransform convert to CSS pixels; r=dzbarsky

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LayerTransactionParent::RecvGetTransform takes care to reverse all the
transformations applied by AsyncCompositionManager::SampleValue to the CSS
values calculated so that it can return CSS values for testing. However, it
fails to revert the conversion from CSS pixels to device pixels applied to the
translation components of the transform by
nsStyleTransformMatrix::ProcessTranslatePart as called by
nsDisplayTransform::GetResultingTransformMatrix.

This patch converts the resulting transform's translation components from device
pixels back to CSS pixels. It also adds documentation for the other operations
in LayerTransactionParent::RecvGetTransform.
This commit is contained in:
Brian Birtles 2014-03-10 13:47:12 +09:00
parent 41336d20b3
commit e3b4d6f388
1 changed files with 24 additions and 2 deletions
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26
gfx/layers/ipc/LayerTransactionParent.cpp
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@ -32,6 +32,7 @@
#include "mozilla/mozalloc.h" // for operator delete, etc
#include "nsCoord.h" // for NSAppUnitsToFloatPixels
#include "nsDebug.h" // for NS_RUNTIMEABORT
#include "nsDeviceContext.h" // for AppUnitsPerCSSPixel
#include "nsISupportsImpl.h" // for Layer::Release, etc
#include "nsLayoutUtils.h" // for nsLayoutUtils
#include "nsMathUtils.h" // for NS_round
@ -578,12 +579,14 @@ LayerTransactionParent::RecvGetTransform(PLayerParent* aParent,
// The following code recovers the untranslated transform
// from the shadow transform by undoing the translations in
// AsyncCompositionManager::SampleValue.
Layer* layer = cast(aParent)->AsLayer();
if (!layer) {
return false;
}
gfx::To3DMatrix(layer->AsLayerComposite()->GetShadowTransform(), *aTransform);
if (ContainerLayer* c = layer->AsContainerLayer()) {
// Undo the scale transform applied by AsyncCompositionManager::SampleValue
aTransform->ScalePost(1.0f/c->GetInheritedXScale(),
1.0f/c->GetInheritedYScale(),
1.0f);
@ -599,13 +602,32 @@ LayerTransactionParent::RecvGetTransform(PLayerParent* aParent,
gfxPoint3D(NS_round(NSAppUnitsToFloatPixels(data.origin().x, scale)),
NS_round(NSAppUnitsToFloatPixels(data.origin().y, scale)),
0.0f);
transformOrigin = data.transformOrigin();
double cssPerDev =
double(nsDeviceContext::AppUnitsPerCSSPixel()) / double(scale);
transformOrigin = data.transformOrigin() * cssPerDev;
break;
}
}
// Undo the translation to the origin of the reference frame applied by
// AsyncCompositionManager::SampleValue
aTransform->Translate(-scaledOrigin);
*aTransform = nsLayoutUtils::ChangeMatrixBasis(-scaledOrigin - transformOrigin, *aTransform);
// Undo the rebasing applied by
// nsDisplayTransform::GetResultingTransformMatrixInternal
*aTransform =
nsLayoutUtils::ChangeMatrixBasis(-scaledOrigin - transformOrigin,
*aTransform);
// Convert to CSS pixels (this undoes the operations performed by
// nsStyleTransformMatrix::ProcessTranslatePart which is called from
// nsDisplayTransform::GetResultingTransformMatrix)
double devPerCss =
double(scale) / double(nsDeviceContext::AppUnitsPerCSSPixel());
aTransform->_41 *= devPerCss;
aTransform->_42 *= devPerCss;
aTransform->_43 *= devPerCss;
return true;
}