Add support for text-level transformation

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

5 files changed, 26 insertions, 11 deletions

diff --git a/README b/README
index f7327d9..dc282f7 100644
--- a/README
+++ b/README
@@ -36,7 +36,7 @@ Currently implemented:
 
 	sRGB gamma function.
 
-	Affine transformations on glyphs.
+	Affine transformations on glyphs and texts.
 
 
 Pending support in libschift:
@@ -55,8 +55,6 @@ Pending support in libschift:
 
 Not implemented yet
 
-	Affine transformations on texts.
-
 	Glyph caching.
 
 	Normalise text when glyphs are missing.
diff --git a/common.h b/common.h
index 5015efd..5caf373 100644
--- a/common.h
+++ b/common.h
@@ -31,6 +31,9 @@ struct libskrift_context {
 	char                       subpixel_horizontally;
 	char                       subpixel_vertically;
 	char                       subpixel_bgr;
+	double                     x_advancement;
+	double                     y_advancement;
+	double                     transformation[6];
 	size_t                     nfonts;
 	LIBSKRIFT_FONT            *fonts[];
 };
diff --git a/demo.c b/demo.c
index c6a27d2..0d0a866 100644
--- a/demo.c
+++ b/demo.c
@@ -17,13 +17,14 @@ main(void)
 
 	rendering.smoothing      = LIBSKRIFT_SUBPIXEL;
 	rendering.subpixel_order = LIBSKRIFT_NONE;
-	rendering.flags          = LIBSKRIFT_MIRROR_CHARS;
+	rendering.flags          = LIBSKRIFT_MIRROR_CHARS * 0;
 
 	if (libskrift_open_font_file(&font, DEMO_FONT)) {
 		perror("libskrift_open_font_file");
 		return -1;
 	}
-	libskrift_add_rotation_degrees(rendering.char_transformation, 10);
+	libskrift_add_rotation_degrees(rendering.text_transformation, -10);
+	libskrift_add_shear(rendering.char_transformation, .75f, 0);
 	height = libskrift_points_to_pixels(72, &rendering);
 	if (libskrift_create_context(&ctx, &font, 1, height, &rendering, NULL)) {
 		perror("libskrift_create_context");
diff --git a/libskrift_create_context.c b/libskrift_create_context.c
index 1500b20..f034240 100644
--- a/libskrift_create_context.c
+++ b/libskrift_create_context.c
@@ -39,7 +39,7 @@ transformation_hook(void *hook_data, double advance, double transform[6])
 	double m1[6] = {1, 0, 0, 0, 1, 0}, m2[6] = {1, 0, 0, 0, 1, 0};
 	if (((ctx->rendering.flags / LIBSKRIFT_MIRROR_CHARS) ^ (ctx->rendering.flags / LIBSKRIFT_MIRROR_TEXT)) & 1)
 		multiply_matrices((double []){-1, 0, advance / schrift[0], 0, 1, 0}, m2, m1);
-	multiply_matrices(ctx->rendering.char_transformation, m1, m2);
+	multiply_matrices(ctx->transformation, m1, m2);
 	multiply_matrices(schrift, m2, m1);
 	transform[0] = m1[0];
 	transform[2] = m1[1];
@@ -76,6 +76,8 @@ libskrift_create_context(LIBSKRIFT_CONTEXT **ctxp, LIBSKRIFT_FONT **fonts, size_
 
 	(*ctxp)->schrift_ctx.font   = fonts[0]->font;
 	(*ctxp)->schrift_ctx.yScale = height;
+	(*ctxp)->x_advancement      = 1;
+	(*ctxp)->y_advancement      = 0;
 	(*ctxp)->nfonts             = nfonts;
 	for (i = 0; i < nfonts; i++) {
 		(*ctxp)->fonts[i] = fonts[i];
@@ -90,7 +92,6 @@ libskrift_create_context(LIBSKRIFT_CONTEXT **ctxp, LIBSKRIFT_FONT **fonts, size_
 		COPY_ARRAY((*ctxp)->rendering, default_rendering, top_transformation);
 		COPY_ARRAY((*ctxp)->rendering, default_rendering, bottom_transformation);
 		COPY_ARRAY((*ctxp)->rendering, default_rendering, poststroke_transformation_rotation);
-		COPY_ARRAY((*ctxp)->rendering, default_rendering, text_transformation);
 	} else {
 		memcpy(&(*ctxp)->rendering, &default_rendering, sizeof(default_rendering));
 	}
@@ -116,8 +117,19 @@ libskrift_create_context(LIBSKRIFT_CONTEXT **ctxp, LIBSKRIFT_FONT **fonts, size_
 	    fpclassify((*ctxp)->rendering.char_transformation[2]) != FP_ZERO ||
 	    fpclassify((*ctxp)->rendering.char_transformation[3]) != FP_ZERO ||
 	    fpclassify((*ctxp)->rendering.char_transformation[4] - 1) != FP_ZERO ||
-	    fpclassify((*ctxp)->rendering.char_transformation[5]) != FP_ZERO)
+	    fpclassify((*ctxp)->rendering.char_transformation[5]) != FP_ZERO ||
+	    fpclassify((*ctxp)->rendering.text_transformation[0] - 1) != FP_ZERO ||
+	    fpclassify((*ctxp)->rendering.text_transformation[1]) != FP_ZERO ||
+	    fpclassify((*ctxp)->rendering.text_transformation[2]) != FP_ZERO ||
+	    fpclassify((*ctxp)->rendering.text_transformation[3]) != FP_ZERO ||
+	    fpclassify((*ctxp)->rendering.text_transformation[4] - 1) != FP_ZERO ||
+	    fpclassify((*ctxp)->rendering.text_transformation[5]) != FP_ZERO) {
+		memcpy((*ctxp)->transformation, (*ctxp)->rendering.char_transformation, sizeof((*ctxp)->transformation));
+		libskrift_add_transformation((*ctxp)->transformation, (*ctxp)->rendering.text_transformation);
+		(*ctxp)->x_advancement = (*ctxp)->rendering.text_transformation[0];
+		(*ctxp)->y_advancement = (*ctxp)->rendering.text_transformation[3];
 		(*ctxp)->schrift_ctx.transformation_hook = transformation_hook;
+	}
 
 	if ((*ctxp)->rendering.smoothing == LIBSKRIFT_SUBPIXEL) {
 		if ((*ctxp)->rendering.subpixel_order == LIBSKRIFT_RGB) {
diff --git a/libskrift_draw_text.c b/libskrift_draw_text.c
index 8f46df4..95fd523 100644
--- a/libskrift_draw_text.c
+++ b/libskrift_draw_text.c
@@ -7,17 +7,18 @@ libskrift_draw_text(LIBSKRIFT_CONTEXT *ctx, const char *text, const struct libsk
 {
 	struct libskrift_saved_grapheme saved = LIBSKRIFT_NO_SAVED_GRAPHEME;
 	struct libskrift_glyph *glyph;
-	double xpos = 0;
+	double xpos = 0, ypos = 0;
 	ssize_t len;
 	int r;
 
 	for (; *text; text += len) {
-		len = libskrift_get_cluster_glyph(ctx, text, &saved, xpos, 0, &glyph);
+		len = libskrift_get_cluster_glyph(ctx, text, &saved, xpos, ypos, &glyph);
 		if (len < 0)
 			return -1;
 
 		r = libskrift_apply_glyph(ctx, glyph, colour, x, y, image);
-		xpos += glyph->advance;
+		xpos += glyph->advance * ctx->x_advancement;
+		ypos += glyph->advance * ctx->y_advancement;
 		free(glyph);
 		if (r)
 			return -1;