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fix negative zoom factor bug (10636), more comments

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This commit is contained in:
Brian 2007-04-14 07:49:21 -06:00
parent 8d8a3cc398
commit e19cfabb6e
1 changed files with 11 additions and 3 deletions
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14
src/mesa/swrast/s_zoom.c
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@ -37,8 +37,9 @@
* Compute the bounds of the region resulting from zooming a pixel span.
* The resulting region will be entirely inside the window/scissor bounds
* so no additional clipping is needed.
* \param imageX, imageY position of the overall image being drawn
* \param imageX, imageY position of the mage being drawn (gl WindowPos)
* \param spanX, spanY position of span being drawing
* \param width number of pixels in span
* \param x0, x1 returned X bounds of zoomed region [x0, x1)
* \param y0, y1 returned Y bounds of zoomed region [y0, y1)
* \return GL_TRUE if any zoomed pixels visible, GL_FALSE if totally clipped
@ -98,7 +99,11 @@ compute_zoomed_bounds(GLcontext *ctx, GLint imageX, GLint imageY,
/**
* Can use this for unzooming X or Y values.
* Convert a zoomed x image coordinate back to an unzoomed x coord.
* 'zx' is screen position of a pixel in the zoomed image, who's left edge
* is at 'imageX'.
* return corresponding x coord in the original, unzoomed image.
* This can use this for unzooming X or Y values.
*/
static INLINE GLint
unzoom_x(GLfloat zoomX, GLint imageX, GLint zx)
@ -108,7 +113,10 @@ unzoom_x(GLfloat zoomX, GLint imageX, GLint zx)
zx - imageX = (x - imageX) * zoomX;
(zx - imageX) / zoomX = x - imageX;
*/
GLint x = imageX + (GLint) ((zx - imageX) / zoomX);
GLint x;
if (zoomX < 0.0)
zx++;
x = imageX + (GLint) ((zx - imageX) / zoomX);
return x;
}