System and method for framework clipping
View Patent ↗A method and system for framework clipping are disclosed. A user interface tree of widgets corresponding to widgets requiring clipping is traversed. For each encountered widget, layer allocation operations are performed which include selecting a current, previous, or next layer to which to allocate the widget and determining whether the selected layer can accommodate the widget, where a determination that the selected layer cannot accommodate the widget results in a bit from a stencil buffer being allocated to the selected layer. A value of the selected layer is incremented to account for the widget being allocated to the selected layer A stencil test mask is generated as a combination of value of the layers previous to a current layer. The stencil test mask is written to the stencil buffer, and the layer allocation operations are repeated for each remaining widget.
1. A method, comprising:
traversing a user interface tree of widgets corresponding to widgets requiring clipping that are present in a scene to be rendered;
for each encountered widget, performing layer allocation operations comprising:
selecting a current, previous, or next layer to which to allocate the widget;
determining whether the selected layer can accommodate the widget;
based on a determination that the selected layer cannot accommodate the widget,
allocating a bit from a stencil buffer to the selected layer and incrementing a value of the selected layer to account for the widget being allocated to the selected layer;
based on a determination that the selected layer can accommodate the widget, incrementing the value of the selected layer to account for the widget being allocated to the selected layer;
generating a stencil test mask formed as a combination of the values of layers previous to a current layer;
writing the stencil test mask to a stencil buffer; and
repeating the layer allocation operations for each remaining widget,
generating, by a processor, a reference layer comprising a logical OR of the current value of all layers;
generating a draw test mask comprising bits of the stencil buffer that are allocated to all layers;
applying the draw test mask to the stencil buffer;
passing contents of the stencil buffer to a frame buffer for drawing a pixel;
generating a write mask that contains bits allocated to the current laver, the write mask preventing writing to other layers; and
applying both the stencil test mask and the draw test mask to the reference layer and the current value of the stencil buffer before the pixel is drawn.
2. The method of claim 1 , wherein each layer supports 2 n-1 widgets, wherein n is the number of bits allocated to the layer.
3. The method of claim 1 , further comprising:
based on a selection of a previous layer to which to allocate the widget, resetting the value of the current layer to zero.
4. The method of claim 1 , wherein the stencil buffer has 8 bits.
5. The method of claim 1 , wherein the value of the current layer is set as writeable to the stencil buffer and the values of the other layers are set as non-writeable to the stencil buffer.
6. A non-transitory machine-readable storage medium storing a set of instructions that, when executed by at least one processor, causes the at least one processor to perform operations comprising:
traversing a user interface tree of widgets corresponding to widgets requiring clipping that are present in a scene to be rendered;
for each encountered widget, performing layer allocation operations comprising:
selecting a current, previous, or next layer to which to allocate the widget;
determining whether the selected layer can accommodate the widget;
based on a determination that the selected layer cannot accommodate the widget, allocating a bit from a stencil buffer to the selected layer and incrementing a value of the selected layer to account for the widget being allocated to the selected layer;
based on a determination that the selected layer can accommodate the widget, incrementing the value of the selected layer to account for the widget being allocated to the selected layer;
generating a stencil test mask formed as a combination of the values of layers previous to a current layer;
writing the stencil test mask to a stencil buffer; and
repeating the layer allocation operations for each remaining widget,
generating a reference layer comprising a logical OR of the current value of all layers;
generating a draw test mask comprising bits of the stencil buffer that are allocated to all layers;
applying the draw test mask to the stencil buffer;
passing contents of the stencil buffer to a frame buffer for drawing a pixel;
generating a write mask that contains bits allocated to the current layer, the write mask preventing writing to other layers: and
applying both the stencil test mask and the draw test mask to the reference layer and the current value of the stencil buffer before the pixel is drawn.
7. The machine-readable storage medium of claim 6 , wherein each layer supports 2 n-1 widgets, wherein n is the number of bits allocated to the layer.
8. The machine-readable storage medium of claim 6 , further comprising:
based on a selection of a previous layer to which to allocate the widget, resetting the value of the current layer to zero.
9. The machine-readable storage medium of claim 6 , wherein the stencil buffer has 8 bits.
10. The machine-readable storage medium of claim 6 , wherein the value of the current layer is set as writeable to the stencil buffer and the values of the other layers are set as non-writeable to the stencil buffer.
11. A system, comprising:
at least one processor;
a framework clipping module implemented by the at least one processor and configured to:
traverse a user interface tree of widgets corresponding to widgets requiring clipping that are present in a scene to be rendered;
for each encountered widget, perform layer allocation operations comprising:
select a current, previous, or next layer to which to allocate the widget;
determine whether the selected layer can accommodate the widget;
based on a determination that the selected layer cannot accommodate the widget, allocate a bit from a stencil buffer to the selected layer and incrementing a value of the selected layer to account for the widget being allocated to the selected layer;
based on a determination that the selected layer can accommodate the widget, increment the value of the selected layer to account for the widget being allocated to the selected layer;
generate a stencil test mask formed as a combination of the values of layers previous to a current layer;
write the stencil test mask to a stencil buffer; and
repeat the layer allocation operations for each remaining widget,
generate a reference layer comprising a logical OR of the current value of all layers;
generate a draw test mask comprising bits of the stencil buffer that are allocated to all layers;
apply the draw test mask to the stencil buffer;
pass contents of the stencil buffer to a frame buffer for drawing a pixel;
generate a write mask that contains bits allocated to the current layer, the write mask preventing writing to other layers; and
apply both the stencil test mask and the draw test mask to the reference layer and the current value of the stencil buffer before the pixel is drawn.
12. The system of claim 11 , wherein each layer supports 2 n-1 widgets, wherein n is the number of bits allocated to the layer.
13. The system of claim 11 , wherein the framework clipping module is further configured to reset the value of the current layer to zero based on a selection of a previous layer to which to allocate the widget.
14. The system of claim 11 , wherein the value of the current layer is set as writeable to the stencil buffer and the values of the other layers are set as non-writeable to the stencil buffer.