From 0c7b65e1569f28ceee74c9b5e348edb3a18aff68 Mon Sep 17 00:00:00 2001
From: John Cupitt <jcupitt@gmail.com>
Date: Mon, 21 Sep 2020 09:29:25 +0100
Subject: [PATCH] allow both dpi and scale to be set for pdfload

pdfload didn't allow both dpi and scale to be set. This patch makes the
two settings combine if both are given.

thanks le0daniel

see https://github.com/libvips/libvips/issues/1824
---
 ChangeLog                 |  1 +
 libvips/foreign/pdfload.c | 26 +++++++++++++++-----------
 2 files changed, 16 insertions(+), 11 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 2c00b499..1eb7cf4c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -5,6 +5,7 @@
 - in jpegsave, don't set JFIF resolution if we set EXIF resolution
 - bump minimum libheif version to 1.3 [lovell]
 - dzsave in iiif mode could set info.json dimensions off by one [Linden6]
+- pdfload allows dpi and scale to both be set [le0daniel]
 
 9/8/20 started 8.10.1
 - fix markdown -> xml conversion in doc generation
diff --git a/libvips/foreign/pdfload.c b/libvips/foreign/pdfload.c
index 04caef60..b9a66c10 100644
--- a/libvips/foreign/pdfload.c
+++ b/libvips/foreign/pdfload.c
@@ -16,6 +16,8 @@
  * 	- reopen the input if we minimised too early
  * 11/3/20
  * 	- move on top of VipsSource
+ * 21/9/20
+ * 	- allow dpi and scale to both be set [le0daniel]
  */
 
 /*
@@ -109,10 +111,14 @@ typedef struct _VipsForeignLoadPdf {
 	 */
 	double dpi;
 
-	/* Calculate this from DPI. At 72 DPI, we render 1:1 with cairo.
+	/* Scale by this factor.
 	 */
 	double scale;
 
+	/* The total scale factor we render with.
+	 */
+	double total_scale;
+
 	/* Background colour.
 	 */
 	VipsArrayDouble *background;
@@ -170,8 +176,7 @@ vips_foreign_load_pdf_build( VipsObject *object )
 
 	GError *error = NULL;
 
-	if( !vips_object_argument_isset( object, "scale" ) )
-		pdf->scale = pdf->dpi / 72.0;
+	pdf->total_scale = pdf->scale * pdf->dpi / 72.0;
 
 	pdf->stream = vips_g_input_stream_new_from_source( pdf->source );
 	if( !(pdf->doc = poppler_document_new_from_stream( pdf->stream, 
@@ -338,8 +343,8 @@ vips_foreign_load_pdf_header( VipsForeignLoad *load )
 		 * does round to nearest. Without this, things like
 		 * shrink-on-load will break.
 		 */
-		pdf->pages[i].width = VIPS_RINT( width * pdf->scale );
-		pdf->pages[i].height = VIPS_RINT( height * pdf->scale );
+		pdf->pages[i].width = VIPS_RINT( width * pdf->total_scale );
+		pdf->pages[i].height = VIPS_RINT( height * pdf->total_scale );
 
 		if( pdf->pages[i].width > pdf->image.width )
 			pdf->image.width = pdf->pages[i].width;
@@ -421,10 +426,10 @@ vips_foreign_load_pdf_generate( VipsRegion *or,
 		cr = cairo_create( surface );
 		cairo_surface_destroy( surface );
 
-		cairo_scale( cr, pdf->scale, pdf->scale );
+		cairo_scale( cr, pdf->total_scale, pdf->total_scale );
 		cairo_translate( cr, 
-			(pdf->pages[i].left - rect.left) / pdf->scale, 
-			(pdf->pages[i].top - rect.top) / pdf->scale );
+			(pdf->pages[i].left - rect.left) / pdf->total_scale, 
+			(pdf->pages[i].top - rect.top) / pdf->total_scale );
 
 		/* poppler is single-threaded, but we don't need to lock since 
 		 * we're running inside a non-threaded tilecache.
@@ -862,9 +867,8 @@ vips_foreign_load_pdf_is_a( const char *filename )
  * left. Set to -1 to mean "until the end of the document". Use vips_grid() 
  * to change page layout.
  *
- * Use @dpi to set the rendering resolution. The default is 72. Alternatively,
- * you can scale the rendering from the default 1 point == 1 pixel by 
- * setting @scale.
+ * Use @dpi to set the rendering resolution. The default is 72. Additionally,
+ * you can scale by setting @scale. If you set both, they combine.
  *
  * Use @background to set the background RGBA colour. The default is 255 
  * (solid white), use eg. 0 for a transparent background.