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https://gitlab.freedesktop.org/gstreamer/gstreamer.git
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205 lines
4 KiB
C
205 lines
4 KiB
C
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#include "drawmethods.h"
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#define DRAWMETHOD_PLUS(_out,_backbuf,_col) \
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{\
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int tra=0,i=0;\
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unsigned char *bra = (unsigned char*)&(_backbuf);\
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unsigned char *dra = (unsigned char*)&(_out);\
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unsigned char *cra = (unsigned char*)&(_col);\
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for (;i<4;i++) {\
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tra = *cra;\
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tra += *bra;\
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if (tra>255) tra=255;\
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*dra = tra;\
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++dra;++cra;++bra;\
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}\
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}
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#define DRAWMETHOD DRAWMETHOD_PLUS(*p,*p,col)
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void
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draw_line (Pixel * data, int x1, int y1, int x2, int y2, int col, int screenx,
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int screeny)
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{
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int x, y, dx, dy, yy, xx;
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Pixel *p;
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if ((y1 < 0) || (y2 < 0) || (x1 < 0) || (x2 < 0) || (y1 >= screeny)
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|| (y2 >= screeny) || (x1 >= screenx) || (x2 >= screenx))
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return;
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/* clip to top edge
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if ((y1 < 0) && (y2 < 0))
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return;
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if (y1 < 0) {
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x1 += (y1 * (x1 - x2)) / (y2 - y1);
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y1 = 0;
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}
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if (y2 < 0) {
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x2 += (y2 * (x1 - x2)) / (y2 - y1);
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y2 = 0;
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}
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clip to bottom edge
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if ((y1 >= screeny) && (y2 >= screeny))
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return;
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if (y1 >= screeny) {
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x1 -= ((screeny - y1) * (x1 - x2)) / (y2 - y1);
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y1 = screeny - 1;
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}
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if (y2 >= screeny) {
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x2 -= ((screeny - y2) * (x1 - x2)) / (y2 - y1);
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y2 = screeny - 1;
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}
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clip to left edge
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if ((x1 < 0) && (x2 < 0))
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return;
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if (x1 < 0) {
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y1 += (x1 * (y1 - y2)) / (x2 - x1);
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x1 = 0;
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}
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if (x2 < 0) {
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y2 += (x2 * (y1 - y2)) / (x2 - x1);
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x2 = 0;
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}
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clip to right edge
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if ((x1 >= screenx) && (x2 >= screenx))
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return;
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if (x1 >= screenx) {
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y1 -= ((screenx - x1) * (y1 - y2)) / (x2 - x1);
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x1 = screenx - 1;
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}
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if (x2 >= screenx) {
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y2 -= ((screenx - x2) * (y1 - y2)) / (x2 - x1);
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x2 = screenx - 1;
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}
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*/
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dx = x2 - x1;
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dy = y2 - y1;
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if (x1 > x2) {
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int tmp;
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tmp = x1;
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x1 = x2;
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x2 = tmp;
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tmp = y1;
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y1 = y2;
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y2 = tmp;
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dx = x2 - x1;
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dy = y2 - y1;
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}
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/* vertical line */
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if (dx == 0) {
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if (y1 < y2) {
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p = &(data[(screenx * y1) + x1]);
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for (y = y1; y <= y2; y++) {
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DRAWMETHOD;
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p += screenx;
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}
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} else {
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p = &(data[(screenx * y2) + x1]);
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for (y = y2; y <= y1; y++) {
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DRAWMETHOD;
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p += screenx;
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}
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}
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return;
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}
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/* horizontal line */
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if (dy == 0) {
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if (x1 < x2) {
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p = &(data[(screenx * y1) + x1]);
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for (x = x1; x <= x2; x++) {
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DRAWMETHOD;
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p++;
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}
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return;
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} else {
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p = &(data[(screenx * y1) + x2]);
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for (x = x2; x <= x1; x++) {
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DRAWMETHOD;
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p++;
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}
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return;
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}
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}
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/* 1 */
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/* \ */
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/* \ */
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/* 2 */
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if (y2 > y1) {
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/* steep */
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if (dy > dx) {
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dx = ((dx << 16) / dy);
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x = x1 << 16;
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for (y = y1; y <= y2; y++) {
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xx = x >> 16;
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p = &(data[(screenx * y) + xx]);
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DRAWMETHOD;
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if (xx < (screenx - 1)) {
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p++;
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/* DRAWMETHOD; */
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}
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x += dx;
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}
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return;
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}
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/* shallow */
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else {
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dy = ((dy << 16) / dx);
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y = y1 << 16;
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for (x = x1; x <= x2; x++) {
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yy = y >> 16;
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p = &(data[(screenx * yy) + x]);
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DRAWMETHOD;
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if (yy < (screeny - 1)) {
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p += screeny;
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/* DRAWMETHOD; */
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}
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y += dy;
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}
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}
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}
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/* 2 */
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/* / */
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/* / */
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/* 1 */
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else {
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/* steep */
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if (-dy > dx) {
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dx = ((dx << 16) / -dy);
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x = (x1 + 1) << 16;
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for (y = y1; y >= y2; y--) {
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xx = x >> 16;
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p = &(data[(screenx * y) + xx]);
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DRAWMETHOD;
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if (xx < (screenx - 1)) {
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p--;
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/* DRAWMETHOD; */
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}
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x += dx;
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}
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return;
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}
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/* shallow */
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else {
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dy = ((dy << 16) / dx);
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y = y1 << 16;
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for (x = x1; x <= x2; x++) {
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yy = y >> 16;
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p = &(data[(screenx * yy) + x]);
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DRAWMETHOD;
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if (yy < (screeny - 1)) {
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p += screeny;
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/* DRAWMETHOD; */
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}
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y += dy;
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}
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return;
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}
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}
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}
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