+ zx = imageX + (x - imageX) * zoomX;
+ zx - imageX = (x - imageX) * zoomX;
+ (zx - imageX) / zoomX = x - imageX;
+ */
+ GLint x;
+ if (zoomX < 0.0)
+ zx++;
+ x = imageX + (GLint) ((zx - imageX) / zoomX);
+ return x;
+}
+
+
+
+/**
+ * Helper function called from _swrast_write_zoomed_rgba/rgb/
+ * index/depth_span().
+ */
+static void
+zoom_span( GLcontext *ctx, GLint imgX, GLint imgY, const SWspan *span,
+ const GLvoid *src, GLenum format )
+{
+ SWcontext *swrast = SWRAST_CONTEXT(ctx);
+ SWspan zoomed;
+ GLint x0, x1, y0, y1;
+ GLint zoomedWidth;
+
+ if (!compute_zoomed_bounds(ctx, imgX, imgY, span->x, span->y, span->end,
+ &x0, &x1, &y0, &y1)) {
+ return; /* totally clipped */
+ }
+
+ if (!swrast->ZoomedArrays) {
+ /* allocate on demand */
+ swrast->ZoomedArrays = (SWspanarrays *) CALLOC(sizeof(SWspanarrays));
+ if (!swrast->ZoomedArrays)
+ return;
+ }
+
+ zoomedWidth = x1 - x0;
+ ASSERT(zoomedWidth > 0);
+ ASSERT(zoomedWidth <= MAX_WIDTH);
+
+ /* no pixel arrays! must be horizontal spans. */
+ ASSERT((span->arrayMask & SPAN_XY) == 0);
+ ASSERT(span->primitive == GL_BITMAP);
+
+ INIT_SPAN(zoomed, GL_BITMAP);
+ zoomed.x = x0;
+ zoomed.end = zoomedWidth;
+ zoomed.array = swrast->ZoomedArrays;
+ zoomed.array->ChanType = span->array->ChanType;
+ if (zoomed.array->ChanType == GL_UNSIGNED_BYTE)
+ zoomed.array->rgba = (GLchan (*)[4]) zoomed.array->rgba8;
+ else if (zoomed.array->ChanType == GL_UNSIGNED_SHORT)
+ zoomed.array->rgba = (GLchan (*)[4]) zoomed.array->rgba16;
+ else
+ zoomed.array->rgba = (GLchan (*)[4]) zoomed.array->attribs[FRAG_ATTRIB_COL0];
+
+ COPY_4V(zoomed.attrStart[FRAG_ATTRIB_WPOS], span->attrStart[FRAG_ATTRIB_WPOS]);
+ COPY_4V(zoomed.attrStepX[FRAG_ATTRIB_WPOS], span->attrStepX[FRAG_ATTRIB_WPOS]);
+ COPY_4V(zoomed.attrStepY[FRAG_ATTRIB_WPOS], span->attrStepY[FRAG_ATTRIB_WPOS]);
+
+ zoomed.attrStart[FRAG_ATTRIB_FOGC][0] = span->attrStart[FRAG_ATTRIB_FOGC][0];
+ zoomed.attrStepX[FRAG_ATTRIB_FOGC][0] = span->attrStepX[FRAG_ATTRIB_FOGC][0];
+ zoomed.attrStepY[FRAG_ATTRIB_FOGC][0] = span->attrStepY[FRAG_ATTRIB_FOGC][0];
+
+ if (format == GL_RGBA || format == GL_RGB) {
+ /* copy Z info */
+ zoomed.z = span->z;
+ zoomed.zStep = span->zStep;
+ /* we'll generate an array of colorss */
+ zoomed.interpMask = span->interpMask & ~SPAN_RGBA;
+ zoomed.arrayMask |= SPAN_RGBA;
+ zoomed.arrayAttribs |= FRAG_BIT_COL0; /* we'll produce these values */
+ ASSERT(span->arrayMask & SPAN_RGBA);
+ }
+ else if (format == GL_COLOR_INDEX) {
+ /* copy Z info */
+ zoomed.z = span->z;
+ zoomed.zStep = span->zStep;
+ /* we'll generate an array of color indexes */
+ zoomed.interpMask = span->interpMask & ~SPAN_INDEX;
+ zoomed.arrayMask |= SPAN_INDEX;
+ ASSERT(span->arrayMask & SPAN_INDEX);
+ }
+ else if (format == GL_DEPTH_COMPONENT) {
+ /* Copy color info */
+ zoomed.red = span->red;
+ zoomed.green = span->green;
+ zoomed.blue = span->blue;
+ zoomed.alpha = span->alpha;
+ zoomed.redStep = span->redStep;
+ zoomed.greenStep = span->greenStep;
+ zoomed.blueStep = span->blueStep;
+ zoomed.alphaStep = span->alphaStep;
+ /* we'll generate an array of depth values */
+ zoomed.interpMask = span->interpMask & ~SPAN_Z;
+ zoomed.arrayMask |= SPAN_Z;
+ ASSERT(span->arrayMask & SPAN_Z);
+ }
+ else {
+ _mesa_problem(ctx, "Bad format in zoom_span");