Implement libglitter_redistribute_energy_double

Signed-off-by: Mattias Andrée <maandree@kth.se>

3 files changed, 80 insertions, 71 deletions

diff --git a/Makefile b/Makefile
index cb23ead..78ba8ee 100644
--- a/Makefile
+++ b/Makefile
@@ -62,6 +62,7 @@ libglitter_compose_uint64.o: libglitter_compose_double.c
 libglitter_compose_uint8.o: libglitter_compose_uint64.c libglitter_compose_double.c
 libglitter_desaturate_float.o: libglitter_desaturate_double.c
 libglitter_per_channel_desaturate_float.o: libglitter_per_channel_desaturate_double.c
+libglitter_redistribute_energy_float.o: libglitter_redistribute_energy_double.c
 libglitter_split_uint32_raster.o: libglitter_split_uint64_raster.c
 $(TESTS): $(HDR) libglitter.a
 libglitter_compose_float.test: libglitter_compose_double.c
@@ -71,6 +72,7 @@ libglitter_compose_uint64.test: libglitter_compose_double.c
 libglitter_compose_uint8.test: libglitter_compose_uint64.c libglitter_compose_double.c
 libglitter_desaturate_float.test: libglitter_desaturate_double.c
 libglitter_per_channel_desaturate_float.test: libglitter_per_channel_desaturate_double.c
+libglitter_redistribute_energy_float.test: libglitter_redistribute_energy_double.c
 libglitter_split_uint32_raster.test: libglitter_split_uint64_raster.c
 libglitter_get_colour_model_conversion_matrix_float.test: libglitter_get_colour_model_conversion_matrix_double.c
 
diff --git a/libglitter.h b/libglitter.h
index 277b7e4..b7d409a 100644
--- a/libglitter.h
+++ b/libglitter.h
@@ -231,39 +231,56 @@ void libglitter_update_render_context(LIBGLITTER_RENDER_CONTEXT *, size_t);
  * (both are optional) to kernel to blur the text in
  * order to reduce colour fringing
  * 
- * Each raster shall be row-major ordered an shall
- * have horizontally adjacent cells adjacent in memory:
- * the is no space between the cells' memory areas if
+ * The raster shall be row-major ordered an shall have
+ * horizontally adjacent cells adjacent in memory: the
+ * is no space between the cells' memory areas if
  * there is no horizontal space between them in the
  * raster
  * 
- * @param  output          Output subpixel raster, need not be initialised;
- *                         this raster is latter used as the input raster
- *                         for the `libglitter_compose_double` function.
- *                         This raster is assumed to have the height
- *                         `height + (vkernelsize - 1)` and the width
- *                         `width + (hkernelsize - 1)`; the text will be
- *                         offset from the top by `(vkernelsize - 1) / 2`
- *                         cells downward and and from the left by
- *                         `(hkernelsize - 1) / 2` cells rightward
- * @param  input           Input subpixel raster; this raster must have
- *                         a left padding and a right padding of
- *                         `hkernel - 1` zero-initialised cells, as well
- *                         as a top padding and a bottom padding of
- *                         `vkernel - 1` zero-initialised cells. The
- *                         the pointer itself shall point to the first
- *                         pixel, the topmost and leftmost pixel that
- *                         is not part of the padding.
- * @param  output_rowsize  The number of cells a pointer to cell in
- *                         `output` must be offset with to get to the
- *                         cell on the next row but in the same column
- * @param  input_rowsize   The number of cells a pointer to cell in
- *                         `input` must be offset with to get to the
+ * This function will extend the image in raster by
+ * `(hkernelsize - 1) / 2` cells to the left and to
+ * the right, and `(vkernelsize - 1) / 2` cells to
+ * the up as well as down. The caller is responsible
+ * for furthering extending the image by `widthmul`
+ * - (hkernelsize - 1) / 2 % widthmul` cells both to
+ * on the left and on the right, and by `heightmul`
+ * - (vkernelsize - 1) / 2 % heightmul` cells both
+ * up and down (where `widthmul` and `heightmul` are
+ * arguments to the `libglitter_create_render_context`
+ * function); so that the raster can be input to
+ * `libglitter_compose_double`.
+ * 
+ * @param  raster          The subpixel raster. The must be padded with
+ *                         zero-initialised cells on the left side and
+ *                         on the top. This padding must `(hkernelsize - 1)`
+ *                         cells wide the left side and `(vkernelsize - 1)`
+ *                         cells tall on the top. The new image will be
+ *                         written to this raster must shiften upwards
+ *                         `(vkernelsize - 1) / 2` cells and to the left
+ *                         `(hkernelsize - 1) / 2` cells. The image will
+ *                         also be extended by `(hkernelsize - 1) / 2`
+ *                         cells on both the left side and the right size
+ *                         and by `(vkernelsize - 1) / 2` cells both above
+ *                         and below. The input pointer shall point to
+ *                         the image location in the pointer, that is
+ *                         the first cell after the padding, but once
+ *                         the function returns the pointer to first
+ *                         cell is in the padding shall be used as the
+ *                         first cell in the new image; however the image
+ *                         will be offset by `(vkernelsize - 1) / 2` cells
+ *                         vertically and `(hkernelsize - 1) / 2` cells
+ *                         horizontally.
+ * @param  rowsize         The number of cells a pointer to cell in
+ *                         `raster` must be offset with to get to the
  *                         cell on the next row but in the same column
- * @param  width           The width of the input raster, excluding
- *                         padding, in cells
- * @param  height          The height of the input raster, excluding
- *                         padding, in cells
+ * @param  width           The width of the input raster (excluding
+ *                         padding), in cells. The function extends the
+ *                         image by `(hkernelsize - 1) / 2` cells
+ *                         vertically.
+ * @param  height          The height of the input raster (excluding
+ *                         padding), in cells. The function extends the
+ *                         image by `(hkernelsize - 1) / 2` cells
+ *                         horizontally.
  * @param  hkernelsize     The size (number of elements) of `hkernel`;
  *                         must be odd; if 1, `hkernel` is not applied
  * @param  vkernelsize     The size (number of elements) of `vkernel`;
@@ -287,9 +304,8 @@ void libglitter_update_render_context(LIBGLITTER_RENDER_CONTEXT *, size_t);
  * `vkernel` is `{1/3., 1/3., 1/3.}`. Of course user
  * experimentation is required to find the best kernel.
  */
-LIBGLITTER_GCC_ATTRS__(nonnull(1, 2))
-void libglitter_redistribute_energy_double(double *restrict output, const double *restrict input,
-                                           size_t output_rowsize, size_t input_rowsize, size_t width,
+LIBGLITTER_GCC_ATTRS__(nonnull(1))
+void libglitter_redistribute_energy_double(double *restrict raster, size_t rowsize, size_t width,
                                            size_t height, size_t hkernelsize, size_t vkernelsize,
                                            const double *hkernel, const double *vkernel);
 
@@ -298,9 +314,8 @@ void libglitter_redistribute_energy_double(double *restrict output, const double
  * apart from it parameter types, see `libglitter_redistribute_energy_double`
  * for details about this function
  */
-LIBGLITTER_GCC_ATTRS__(nonnull(1, 2))
-void libglitter_redistribute_energy_float(float *restrict output, const float *restrict input,
-                                          size_t output_rowsize, size_t input_rowsize, size_t width,
+LIBGLITTER_GCC_ATTRS__(nonnull(1))
+void libglitter_redistribute_energy_float(float *restrict raster, size_t rowsize, size_t width,
                                           size_t height, size_t hkernelsize, size_t vkernelsize,
                                           const float *hkernel, const float *vkernel);
 
diff --git a/libglitter_redistribute_energy_double.c b/libglitter_redistribute_energy_double.c
index 3eb39e0..9f97ed3 100644
--- a/libglitter_redistribute_energy_double.c
+++ b/libglitter_redistribute_energy_double.c
@@ -4,56 +4,48 @@
 
 
 static void
-hselfconvolute(double *restrict raster, size_t rowsize, size_t width, size_t height, size_t kernelsize, const double *hkernel)
+vconvolute(double *restrict raster, size_t rowsize, size_t width, size_t height, size_t kernelsize, const double *kernel)
 {
-	/* TODO */
-}
-
-
-static void
-hconvolute(double *restrict output, const double *restrict input, size_t output_rowsize, size_t input_rowsize,
-           size_t width, size_t height, size_t kernelsize, const double *kernel)
-{
-	/* TODO */
-}
-
-
-static void
-vconvolute(double *restrict output, const double *restrict input, size_t output_rowsize, size_t input_rowsize,
-           size_t width, size_t height, size_t kernelsize, const double *kernel)
-{
-	/* TODO */
+	size_t y, x, i;
+	for (y = 0; y < height; y++) {
+		for (x = 0; x < width; x++)
+			raster[x] *= kernel[0];
+		for (i = 1; i < kernelsize; i++)
+			for (x = 0; x < width; x++)
+				raster[x] = fma(raster[i * rowsize + x], kernel[i], raster[x]);
+		raster = &raster[rowsize];
+	}
 }
 
 
 static void
-copyraster(double *restrict output, const double *restrict input, size_t output_rowsize,
-           size_t input_rowsize, size_t width, size_t height)
+hconvolute(double *restrict raster, size_t rowsize, size_t width, size_t height, size_t kernelsize, const double *kernel)
 {
-	size_t y;
+	size_t y, x, i;
 	for (y = 0; y < height; y++) {
-		memcpy(output, input, width * sizeof(double));
-		output = &output[output_rowsize];
-		input = &input[input_rowsize];
+		for (x = 0; x < width; x++) {
+			raster[x] *= kernel[0];
+			for (i = 1; i < kernelsize; i++)
+				raster[x] = fma(raster[x + i], kernel[i], raster[x]);
+		}
+		raster = &raster[rowsize];
 	}
 }
 
 
 void
-libglitter_redistribute_energy_double(double *restrict output, const double *restrict input, /* TODO add man page */
-                                      size_t output_rowsize, size_t input_rowsize, size_t width,
-                                      size_t height, size_t hkernelsize, size_t vkernelsize,
-                                      const double *hkernel, const double *vkernel)
+libglitter_redistribute_energy_double(double *restrict raster, size_t rowsize, size_t width, size_t height, /* TODO add man page */
+                                      size_t hkernelsize, size_t vkernelsize, const double *hkernel, const double *vkernel)
 {
-	/* TODO Can we allow output==input ? */
 	if (vkernelsize > 1) {
-		vconvolute(output, input, output_rowsize, input_rowsize, width, height, vkernelsize, vkernel);
-		if (hkernelsize > 1)
-			hselfconvolute(output, output_rowsize, width, height, hkernelsize, hkernel);
-	} else if (hkernelsize > 1) {
-		vconvolute(output, input, output_rowsize, input_rowsize, width, height, hkernelsize, hkernel);
-	} else {
-		copyraster(output, input, output_rowsize, input_rowsize, width, height);
+		raster -= (hkernelsize - 1) * rowsize;
+		vconvolute(raster, rowsize, width, height, vkernelsize, vkernel);
+		height += hkernelsize - 1;
+	}
+	if (hkernelsize > 1) {
+		raster -= hkernelsize - 1;
+		hconvolute(raster, rowsize, width, height, hkernelsize, hkernel);
+		width += hkernelsize - 1;
 	}
 }