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/* Copyright (c) 2012 The Chromium Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
/**
* Defines the <code>PPB_Graphics2D</code> struct representing a 2D graphics
* context within the browser.
*/
label Chrome {
M14 = 1.0
};
/**
* <code>PPB_Graphics2D</code> defines the interface for a 2D graphics context.
*/
[macro="PPB_GRAPHICS_2D_INTERFACE"]
interface PPB_Graphics2D {
/**
* Create() creates a 2D graphics context. The returned graphics context will
* not be bound to the module instance on creation (call BindGraphics() on
* the module instance to bind the returned graphics context to the module
* instance).
*
* @param[in] instance The module instance.
* @param[in] size The size of the graphic context.
* @param[in] is_always_opaque Set the <code>is_always_opaque</code> flag to
* <code>PP_TRUE</code> if you know that you will be painting only opaque
* data to this context. This option will disable blending when compositing
* the module with the web page, which might give higher performance on some
* computers.
*
* If you set <code>is_always_opaque</code>, your alpha channel should always
* be set to 0xFF or there may be painting artifacts. The alpha values
* overwrite the destination alpha values without blending when
* <code>is_always_opaque</code> is true.
*
* @return A <code>PP_Resource</code> containing the 2D graphics context if
* successful or 0 if unsuccessful.
*/
PP_Resource Create(
[in] PP_Instance instance,
[in] PP_Size size,
[in] PP_Bool is_always_opaque);
/**
* IsGraphics2D() determines if the given resource is a valid
* <code>Graphics2D</code>.
*
* @param[in] resource A <code>Graphics2D</code> context resource.
*
* @return PP_TRUE if the given resource is a valid <code>Graphics2D</code>,
* <code>PP_FALSE</code> if it is an invalid resource or is a resource of
* another type.
*/
PP_Bool IsGraphics2D(
[in] PP_Resource resource);
/**
* Describe() retrieves the configuration for the given graphics context,
* filling the given values (which must not be <code>NULL</code>).
*
* @param[in] resource The 2D Graphics resource.
* @param[in,out] size The size of the 2D graphics context in the browser.
* @param[in,out] is_always_opaque Identifies whether only opaque data
* will be painted.
*
* @return Returns <code>PP_TRUE</code> on succes or <code>PP_FALSE</code> if
* the resource is invalid. The output parameters will be set to 0 on a
* <code>PP_FALSE</code>.
*/
PP_Bool Describe(
[in] PP_Resource graphics_2d,
[out] PP_Size size,
[out] PP_Bool is_always_opqaue);
/**
* PaintImageData() enqueues a paint of the given image into the context.
* This function has no effect until you call Flush() As a result, what
* counts is the contents of the bitmap when you call Flush(), not when
* you call this function.
*
* The provided image will be placed at <code>top_left</code> from the top
* left of the context's internal backing store. Then the pixels contained
* in <code>src_rect</code> will be copied into the backing store. This
* means that the rectangle being painted will be at <code>src_rect</code>
* offset by <code>top_left</code>.
*
* The <code>src_rect</code> is specified in the coordinate system of the
* image being painted, not the context. For the common case of copying the
* entire image, you may specify an empty <code>src_rect</code>.
*
* The painted area of the source bitmap must fall entirely within the
* context. Attempting to paint outside of the context will result in an
* error. However, the source bitmap may fall outside the context, as long
* as the <code>src_rect</code> subset of it falls entirely within the
* context.
*
* There are two methods most modules will use for painting. The first
* method is to generate a new <code>ImageData</code> and then paint it. In
* this case, you'll set the location of your painting to
* <code>top_left</code> and set <code>src_rect</code> to <code>NULL</code>.
* The second is that you're generating small invalid regions out of a larger
* bitmap representing your entire instance. In this case, you would set the
* location of your image to (0,0) and then set <code>src_rect</code> to the
* pixels you changed.
*
* @param[in] resource The 2D Graphics resource.
* @param[in] image The <code>ImageData</code> to be painted.
* @param[in] top_left A <code>Point</code> representing the
* <code>top_left</code> location where the <code>ImageData</code> will be
* painted.
* @param[in] src_rect The rectangular area where the <code>ImageData</code>
* will be painted.
*/
void PaintImageData(
[in] PP_Resource graphics_2d,
[in] PP_Resource image_data,
[in] PP_Point top_left,
[in] PP_Rect src_rect);
/**
* Scroll() enqueues a scroll of the context's backing store. This
* function has no effect until you call Flush(). The data within the
* provided clipping rectangle will be shifted by (dx, dy) pixels.
*
* This function will result in some exposed region which will have undefined
* contents. The module should call PaintImageData() on these exposed regions
* to give the correct contents.
*
* The scroll can be larger than the area of the clipping rectangle, which
* means the current image will be scrolled out of the rectangle. This
* scenario is not an error but will result in a no-op.
*
* @param[in] graphics_2d The 2D Graphics resource.
* @param[in] clip The clipping rectangle.
* @param[in] amount The amount the area in the clipping rectangle will
* shifted.
*/
void Scroll(
[in] PP_Resource graphics_2d,
[in] PP_Rect clip_rect,
[in] PP_Point amount);
/**
* ReplaceContents() provides a slightly more efficient way to paint the
* entire module's image. Normally, calling PaintImageData() requires that
* the browser copy the pixels out of the image and into the graphics
* context's backing store. This function replaces the graphics context's
* backing store with the given image, avoiding the copy.
*
* The new image must be the exact same size as this graphics context. If the
* new image uses a different image format than the browser's native bitmap
* format (use <code>PPB_ImageData.GetNativeImageDataFormat()</code> to
* retrieve the format), then a conversion will be done inside the browser
* which may slow the performance a little bit.
*
* <strong>Note:</strong> The new image will not be painted until you call
* Flush().
*
* After this call, you should take care to release your references to the
* image. If you paint to the image after ReplaceContents(), there is the
* possibility of significant painting artifacts because the page might use
* partially-rendered data when copying out of the backing store.
*
* In the case of an animation, you will want to allocate a new image for the
* next frame. It is best if you wait until the flush callback has executed
* before allocating this bitmap. This gives the browser the option of
* caching the previous backing store and handing it back to you (assuming
* the sizes match). In the optimal case, this means no bitmaps are allocated
* during the animation, and the backing store and "front buffer" (which the
* plugin is painting into) are just being swapped back and forth.
*
* @param[in] graphics_2d The 2D Graphics resource.
* @param[in] image The <code>ImageData</code> to be painted.
*/
void ReplaceContents(
[in] PP_Resource graphics_2d,
[in] PP_Resource image_data);
/**
* Flush() flushes any enqueued paint, scroll, and replace commands to the
* backing store. This function actually executes the updates, and causes a
* repaint of the webpage, assuming this graphics context is bound to a module
* instance.
*
* Flush() runs in asynchronous mode. Specify a callback function and the
* argument for that callback function. The callback function will be
* executed on the calling thread when the image has been painted to the
* screen. While you are waiting for a flush callback, additional calls to
* Flush() will fail.
*
* Because the callback is executed (or thread unblocked) only when the
* instance's image is actually on the screen, this function provides
* a way to rate limit animations. By waiting until the image is on the
* screen before painting the next frame, you can ensure you're not
* flushing 2D graphics faster than the screen can be updated.
*
* <strong>Unbound contexts</strong>
* If the context is not bound to a module instance, you will
* still get a callback. The callback will execute after Flush() returns
* to avoid reentrancy. The callback will not wait until anything is
* painted to the screen because there will be nothing on the screen. The
* timing of this callback is not guaranteed and may be deprioritized by
* the browser because it is not affecting the user experience.
*
* <strong>Off-screen instances</strong>
* If the context is bound to an instance that is currently not visible (for
* example, scrolled out of view) it will behave like the "unbound context"
* case.
*
* <strong>Detaching a context</strong>
* If you detach a context from a module instance, any pending flush
* callbacks will be converted into the "unbound context" case.
*
* <strong>Released contexts</strong>
* A callback may or may not get called even if you have released all
* of your references to the context. This scenario can occur if there are
* internal references to the context suggesting it has not been internally
* destroyed (for example, if it is still bound to an instance) or due to
* other implementation details. As a result, you should be careful to
* check that flush callbacks are for the context you expect and that
* you're capable of handling callbacks for unreferenced contexts.
*
* <strong>Shutdown</strong>
* If a module instance is removed when a flush is pending, the
* callback will not be executed.
*
* @param[in] graphics_2d The 2D Graphics resource.
* @param[in] callback A <code>CompletionCallback</code> to be called when
* the image has been painted on the screen.
*
* @return Returns <code>PP_OK</code> on success or
* <code>PP_ERROR_BADRESOURCE</code> if the graphics context is invalid,
* <code>PP_ERROR_BADARGUMENT</code> if the callback is null and flush is
* being called from the main thread of the module, or
* <code>PP_ERROR_INPROGRESS</code> if a flush is already pending that has
* not issued its callback yet. In the failure case, nothing will be updated
* and no callback will be scheduled.
*/
int32_t Flush(
[in] PP_Resource graphics_2d,
[in] PP_CompletionCallback callback);
};
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