Added bitmap transformer to fix blur with rotation and non-uniform scaling

(bzr r2125)

1 files changed, 98 insertions, 0 deletions

diff --git a/src/display/pixblock-transform.cpp b/src/display/pixblock-transform.cpp
new file mode 100644
index 000000000..1a691b5a8
--- /dev/null
+++ b/src/display/pixblock-transform.cpp
@@ -0,0 +1,98 @@
+#define __NR_PIXBLOCK_SCALER_CPP__
+
+/*
+ * Functions for blitting pixblocks using matrix transformation
+ *
+ * Author:
+ *   Niko Kiirala <niko@kiirala.com>
+ *
+ * Copyright (C) 2006 Niko Kiirala
+ *
+ * Released under GNU GPL, read the file 'COPYING' for more information
+ */
+
+#include <glib.h>
+#include <cmath>
+using std::floor;
+
+#include "libnr/nr-pixblock.h"
+#include "libnr/nr-matrix.h"
+
+namespace NR {
+
+struct RGBA {
+    int r, g, b, a;
+};
+
+/**
+ * Sanity check function for indexing pixblocks.
+ * Catches reading and writing outside the pixblock area.
+ * When enabled, decreases filter rendering speed massively.
+ */
+inline void _check_index(NRPixBlock const * const pb, int const location, int const line)
+{
+    if(true) {
+        int max_loc = pb->rs * (pb->area.y1 - pb->area.y0);
+        if (location < 0 || (location + 4) >= max_loc)
+            g_warning("Location %d out of bounds (0 ... %d) at line %d", location, max_loc, line);
+    }
+}
+
+void transform_nearest(NRPixBlock *to, NRPixBlock *from, Matrix &trans)
+{
+    if (NR_PIXBLOCK_BPP(from) != 4 || NR_PIXBLOCK_BPP(to) != 4) {
+        g_warning("A non-32-bpp image passed to transform_nearest: scaling aborted.");
+        return;
+    }
+
+    // Precalculate sizes of source and destination pixblocks
+    int from_width = from->area.x1 - from->area.x0;
+    int from_height = from->area.y1 - from->area.y0;
+    int to_width = to->area.x1 - to->area.x0;
+    int to_height = to->area.y1 - to->area.y0;
+
+    Matrix itrans = trans.inverse();
+
+    // Loop through every pixel of destination image, a line at a time
+    for (int to_y = 0 ; to_y < to_height ; to_y++) {
+        for (int to_x = 0 ; to_x < to_width ; to_x++) {
+            RGBA result = {0,0,0,0};
+
+            int from_x = (int)round(itrans[0] * (to_x + to->area.x0)
+                                    + itrans[2] * (to_y + to->area.y0)
+                                    + itrans[4]);
+            from_x -= from->area.x0;
+            int from_y = (int)round(itrans[1] * (to_x + to->area.x0)
+                                    + itrans[3] * (to_y + to->area.y0)
+                                    + itrans[5]);
+            from_y -= from->area.y0;
+
+            if (from_x >= 0 && from_x < from_width
+                && from_y >= 0 && from_y < from_height) {
+                _check_index(from, from_y * from->rs + from_x * 4, __LINE__);
+                result.r = NR_PIXBLOCK_PX(from)[from_y * from->rs + from_x * 4];
+                result.g = NR_PIXBLOCK_PX(from)[from_y * from->rs + from_x * 4 + 1];
+                result.b = NR_PIXBLOCK_PX(from)[from_y * from->rs + from_x * 4 + 2];
+                result.a = NR_PIXBLOCK_PX(from)[from_y * from->rs + from_x * 4 + 3];
+            }
+
+            _check_index(to, to_y * to->rs + to_x * 4, __LINE__);
+            NR_PIXBLOCK_PX(to)[to_y * to->rs + to_x * 4] = result.r;
+            NR_PIXBLOCK_PX(to)[to_y * to->rs + to_x * 4 + 1] = result.g;
+            NR_PIXBLOCK_PX(to)[to_y * to->rs + to_x * 4 + 2] = result.b;
+            NR_PIXBLOCK_PX(to)[to_y * to->rs + to_x * 4 + 3] = result.a;
+        }
+    }
+}
+
+} /* namespace NR */
+/*
+  Local Variables:
+  mode:c++
+  c-file-style:"stroustrup"
+  c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
+  indent-tabs-mode:nil
+  fill-column:99
+  End:
+*/
+// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=99 :