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1f17665741
The LowerRightX and LowerRightY were calculated as the X and Y coordinates of the pixel to the right and below the last visible pixel, but are compared with the last actually visible pixel in the source. They need an extra -1 offset to correct. Add comments to explain what's going on. Fix the signature of the function to reflect that the "dummy" passed for the display region is a pointer not an integer.
88 lines
2.7 KiB
C
88 lines
2.7 KiB
C
/* $Id: xbbt.c,v 1.2 1999/01/03 02:07:46 sybalsky Exp $ (C) Copyright Venue, All Rights Reserved */
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/************************************************************************/
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/* */
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/* (C) Copyright 1989, 1990, 1990, 1991, 1992, 1993, 1994, 1995 Venue. */
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/* All Rights Reserved. */
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/* Manufactured in the United States of America. */
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/* */
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/************************************************************************/
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#include "version.h"
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#include <stdio.h>
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#include <X11/Xlib.h>
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#include <X11/Xutil.h>
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#include "lispemul.h"
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#include "xdefs.h"
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#include "devif.h"
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#include "xbbtdefs.h"
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/************************************************************************/
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/* */
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/* c l i p p i n g _ X b i t b l t */
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/* */
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/* BITBLT from the display region to the X server's display, */
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/* clipping to fit the window we're in on the server. */
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/* */
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/* dummy is the placeholder for the bitmap to be blitted */
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/* */
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/************************************************************************/
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unsigned long clipping_Xbitblt(DspInterface dsp, DLword *dummy, int x, int y, int w, int h)
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{
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int temp_x, temp_y, LowerRightX, LowerRightY;
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LowerRightX = dsp->Visible.x + dsp->Visible.width - 1;
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LowerRightY = dsp->Visible.y + dsp->Visible.height - 1;
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/* display region of interest lower right x, y pixel */
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temp_x = x + w - 1;
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temp_y = y + h - 1;
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/* if the display region of interest is completely outside the visible window */
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if ((temp_x < dsp->Visible.x) || (x > LowerRightX) || (temp_y < dsp->Visible.y) ||
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(y > LowerRightY))
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return (0);
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/* if the display region of interest is completely within the visible window */
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if ((x >= dsp->Visible.x) && (temp_x <= LowerRightX) && (y >= dsp->Visible.y) &&
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(temp_y <= LowerRightY)) {
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XLOCK;
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XPutImage(dsp->display_id, dsp->DisplayWindow, dsp->Copy_GC, &dsp->ScreenBitmap, x, y,
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x - dsp->Visible.x, y - dsp->Visible.y, w, h);
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XFlush(dsp->display_id);
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XUNLOCK;
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return (1);
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}
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/* clip left to visible window */
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if (x < dsp->Visible.x) {
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w -= dsp->Visible.x - x;
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x = dsp->Visible.x;
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}
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/* clip right to visible window */
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if (temp_x > LowerRightX) w -= temp_x - LowerRightX;
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/* clip top to visible window */
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if (y < dsp->Visible.y) {
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h -= dsp->Visible.y - y;
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y = dsp->Visible.y;
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}
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/* clip bottom to visible window */
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if (temp_y > LowerRightY) h -= temp_y - LowerRightY;
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if ((w > 0) && (h > 0)) {
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XLOCK;
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XPutImage(dsp->display_id, dsp->DisplayWindow, dsp->Copy_GC, &dsp->ScreenBitmap, x, y,
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x - dsp->Visible.x, y - dsp->Visible.y, w, h);
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XFlush(dsp->display_id);
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XUNLOCK;
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}
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return (1);
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} /* end clipping_Xbitblt */
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