Add fz_transform_page helper function.

Create a matrix that transforms a page with resolution and rotation,
and grid fits the resulting bounding box.

1 files changed, 23 insertions, 0 deletions

diff --git a/source/fitz/geometry.c b/source/fitz/geometry.c
index e31a9435..96a46102 100644
--- a/source/fitz/geometry.c
+++ b/source/fitz/geometry.c
@@ -211,6 +211,29 @@ fz_pre_translate(fz_matrix m, float tx, float ty)
 }
 
 fz_matrix
+fz_transform_page(fz_rect mediabox, float resolution, float rotate)
+{
+	float user_w, user_h, pixel_w, pixel_h;
+	fz_rect pixel_box;
+	fz_matrix matrix;
+
+	/* Adjust scaling factors to cover whole pixels */
+	user_w = mediabox.x1 - mediabox.x0;
+	user_h = mediabox.y1 - mediabox.y0;
+	pixel_w = floorf(user_w * resolution / 72 + 0.5f);
+	pixel_h = floorf(user_h * resolution / 72 + 0.5f);
+
+	matrix = fz_pre_rotate(fz_scale(pixel_w / user_w, pixel_h / user_h), rotate);
+
+	/* Adjust the page origin to sit at 0,0 after rotation */
+	pixel_box = fz_transform_rect(mediabox, matrix);
+	matrix.e -= pixel_box.x0;
+	matrix.f -= pixel_box.y0;
+
+	return matrix;
+}
+
+fz_matrix
 fz_invert_matrix(fz_matrix src)
 {
 	float a = src.a;