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11aaa29a69
... when it is available. Also introduce the new function gdk_rectangle_transform_affine(), which looks like overkill for this purpose, but I'm about to use it elsewhere.
58 lines
1.8 KiB
C
58 lines
1.8 KiB
C
#pragma once
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#include "gdkrectangle.h"
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#include <math.h>
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G_BEGIN_DECLS
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/*
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* gdk_rectangle_transform_affine:
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* @src: the rectangle to transform
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* @scale_x: scale factor in the X direction. The scale factor
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* may be negative or 0.
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* @scale_y: scale factor in the Y direction. The scale factor
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* may be negative or 0.
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* @offset_x: offset of result in X direction.
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* @offset_y: offset of result in Y direction.
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* @dest: (out caller-allocates): destination rectangle, may be
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* identical to @src
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*
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* Does an affine transform of the source rectangle and stores the
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* result in the dest rectangle. If the destination rectangle does
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* not fit on integer bounds, the result will be enlarged to make it
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* fit.
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* (Fun fact: This means with a scale of 0 and an offset of 0.5,
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* the resulting rect will have a width of 1.)
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*
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* The width and height of the result will be positive, even if the
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* src rectangle or the scale were negative.
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*
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* This function can be used with the output of
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* gsk_transform_to_affine().
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**/
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static inline void
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gdk_rectangle_transform_affine (const GdkRectangle *src,
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float scale_x,
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float scale_y,
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float offset_x,
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float offset_y,
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GdkRectangle *dest)
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{
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float x1, x2, y1, y2;
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x1 = offset_x + src->x * scale_x;
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x2 = offset_x + (src->x + src->width) * scale_x;
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y1 = offset_y + src->y * scale_y;
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y2 = offset_y + (src->y + src->height) * scale_y;
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dest->x = floorf (MIN (x1, x2));
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dest->y = floorf (MIN (y1, y2));
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dest->width = ceilf (MAX (x1, x2)) - dest->x;
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dest->height = ceilf (MAX (y1, y2)) - dest->y;
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}
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G_END_DECLS
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