plugin/idl/layer.idl - Issue 6255003: O2D:...

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Issue 6255003: O2D:... (Closed) Base URL: svn://chrome-svn/chrome/trunk/src/o3d/

Patch Set: Created 9 years, 11 months ago

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1 /*	1 /*

2 * Copyright 2010, Google Inc.	2 * Copyright 2010, Google Inc.

3 * All rights reserved.	3 * All rights reserved.

4 *	4 *

5 * Redistribution and use in source and binary forms, with or without	5 * Redistribution and use in source and binary forms, with or without

6 * modification, are permitted provided that the following conditions are	6 * modification, are permitted provided that the following conditions are

7 * met:	7 * met:

8 *	8 *

9 * * Redistributions of source code must retain the above copyright	9 * * Redistributions of source code must retain the above copyright

10 * notice, this list of conditions and the following disclaimer.	10 * notice, this list of conditions and the following disclaimer.

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32 namespace o3d {	32 namespace o3d {

33	33

34 namespace o2d {	34 namespace o2d {

35	35

36 %[	36 %[

37 A Layer is a rectangular region of the O2D canvas to be filled with a	37 A Layer is a rectangular region of the O2D canvas to be filled with a

38 particular Pattern, with automatic clipping based on stacking order.	38 particular Pattern, with automatic clipping based on stacking order.

39 %]	39 %]

40 [nocpp, include="core/cross/cairo/layer.h"] class Layer : ObjectBase {	40 [nocpp, include="core/cross/cairo/layer.h"] class Layer : ObjectBase {

41 %[	41 %[

	42 Available painting operators.

	43

	44 \var PaintOperator,

	45 \li BLEND, Alpha-blend the Pattern on top of lower Layers based on its

	46 alpha channel. (Default)
	fbarchard 2011/01/19 18:51:20 preattenuated or unattenuated alpha? preattenuated or unattenuated alpha? Tristan Schmelcher 2 2011/01/20 00:26:16 I've never heard of preattenuated/unattenuated alp Show quoted text On 2011/01/19 18:51:20, fbarchard wrote: > preattenuated or unattenuated alpha? I've never heard of preattenuated/unattenuated alpha ... do you mean premultiplied/unpremultiplied alpha? Cairo uses premultiplied alpha for everything, but that's just an implementation detail as far as the JS API is concerned. fbarchard 2011/01/20 18:06:05 same thing. preattenuated = premultiplied unattenu same thing. preattenuated = premultiplied unattenuated = unpremultiplied So Cairo is premultiplied. But hardware (o3d) tends to not be. Maybe worth a note. Tristan Schmelcher 2 2011/01/20 20:43:32 It's noted in my new CL to convert to premultiplie Show quoted text On 2011/01/20 18:06:05, fbarchard wrote: > same thing. > preattenuated = premultiplied > unattenuated = unpremultiplied > So Cairo is premultiplied. But hardware (o3d) tends to not be. Maybe worth a > note. It's noted in my new CL to convert to premultiplied alpha in texture_cairo.cc.
	47 \li BLEND_WITH_TRANSPARENCY, Like BLEND, but scale the alpha channel down

	48 based on the alpha property of the Layer as an

	49 additional fractional transparency.
	fbarchard 2011/01/19 18:51:20 is this destination alpha blending? (aka Disney m is this destination alpha blending? (aka Disney method) Tristan Schmelcher 2 2011/01/20 00:26:16 No, just plain old source alpha blending. The _WIT Show quoted text On 2011/01/19 18:51:20, fbarchard wrote: > is this destination alpha blending? (aka Disney method) No, just plain old source alpha blending. The _WITH_TRANSPARENCY version just means that in addition to using the alpha channel of the Pattern we also use the alpha property of the Layer. So the blend function is basically (1 - (pattern alpha * layer alpha)). fbarchard 2011/01/20 18:06:05 Thats basically what I mean by destination alpha. Thats basically what I mean by destination alpha. The alpha in the frame buffer is used. But there are different ways to use that alpha... the most common being disney's method. Just make sure you get the same results as O3d. Tristan Schmelcher 2 2011/01/20 20:43:32 No, "layer alpha" above means the alpha property o Show quoted text On 2011/01/20 18:06:05, fbarchard wrote: > Thats basically what I mean by destination alpha. The alpha in the frame buffer > is used. No, "layer alpha" above means the alpha property of _this_ Layer object, not the per-pixel alpha channel of the destination of the paint operation. The destination's alpha is not used for anything. In fact the destination does not even have an alpha channel at all. Show quoted text > But there are different ways to use that alpha... the most common > being disney's method. > Just make sure you get the same results as O3d. > It does appear to look the same as O3D.
	50 \li COPY, Copy the colour content of the Pattern directly to the

	51 destination, ignoring the alpha channel.

	52 \li COPY_WITH_FADING, Like COPY, but fade the colour to black based on the

	53 alpha property of the Layer as an additional

	54 fractional brightness.
	fbarchard 2011/01/19 18:51:20 just alpha, or full ARGB shading? just alpha, or full ARGB shading? Tristan Schmelcher 2 2011/01/20 00:26:16 I'm not sure what you're referring to here. Show quoted text On 2011/01/19 18:51:20, fbarchard wrote: > just alpha, or full ARGB shading? I'm not sure what you're referring to here. fbarchard 2011/01/20 18:06:05 So the alpha in the destination layer is used to m So the alpha in the destination layer is used to multiply by the ARGB of the source before doing a 'COPY'. The destinations ARGB is replaced by the 'faded' image. Tristan Schmelcher 2 2011/01/20 20:43:32 No, "alpha property of the Layer" means the alpha Show quoted text On 2011/01/20 18:06:05, fbarchard wrote: > So the alpha in the destination layer is used to multiply by the ARGB of the > source before doing a 'COPY'. The destinations ARGB is replaced by the 'faded' > image. No, "alpha property of the Layer" means the alpha property of this Layer object, i.e. the value returned by this->alpha(). That is used to multiply the ARGB of the source to fade the image, and then the destination's ARGB is replaced with that faded image.
	55 %]

	56 enum PaintOperator {

	57 BLEND,

	58 BLEND_WITH_TRANSPARENCY,

	59 COPY,

	60 COPY_WITH_FADING

	61 };

	62

	63 %[

42 The Pattern used to paint this Layer.	64 The Pattern used to paint this Layer.

43 %]	65 %]

44 [getter, setter] Pattern? pattern;	66 [getter, setter] Pattern? pattern;

45	67

46 %[	68 %[

47 Transparancy of this layer.	69 Whether this layer should be visible or not.

	70 %]

	71 [getter, setter] bool visible;

	72

	73 %[

	74 The transparency for the BLEND_WITH_TRANSPARENCY operator or the fading for

	75 the COPY_WITH_FADING operator.

48 %]	76 %]

49 [getter, setter] double alpha;	77 [getter, setter] double alpha;

50	78

51 %[	79 %[

52 The x coordinate of the top-left corner of this layer.	80 The x coordinate of the top-left corner of this layer.

53 %]	81 %]

54 [getter, setter] double x;	82 [getter, setter] double x;

55	83

56 %[	84 %[

57 The y coordinate of the top-left corner of this layer.	85 The y coordinate of the top-left corner of this layer.

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75	103

76 %[	104 %[

77 A scaling factor to apply to the pattern's x-axis.	105 A scaling factor to apply to the pattern's x-axis.

78 %]	106 %]

79 [getter, setter] double scale_x;	107 [getter, setter] double scale_x;

80	108

81 %[	109 %[

82 A scaling factor to apply to the pattern's y-axis.	110 A scaling factor to apply to the pattern's y-axis.

83 %]	111 %]

84 [getter, setter] double scale_y;	112 [getter, setter] double scale_y;

	113

	114 %[

	115 The paint operator to use for painting this Layer.

	116 %]

	117 [getter, setter] PaintOperator paint_operator;

85 }; // Layer	118 }; // Layer

86	119

87 } // namespace o2d	120 } // namespace o2d

88	121

89 } // namespace o3d	122 } // namespace o3d

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