switch svgload to random access

and fix up pdfload random access

libvips/foreign/pdfiumload.c

@@ -637,11 +637,13 @@ vips_foreign_load_pdf_load( VipsForeignLoad *load )
 		return( -1 );
 
 	/* PDFium does not like rendering parts of pages :-( always render
-	 * complete ones. 
+	 * complete pages. 
 	 */
-	if( vips_linecache( t[0], &t[1],
+	if( vips_tilecache( t[0], &t[1],
-		"tile_height", pdf->pages[0].height, 
+		"tile_width", pdf->pages[0].width,
-		NULL ) ) 
+		"tile_height", pdf->pages[0].height,
+		"max_tiles", 1,
+		NULL ) )
 		return( -1 );
 	if( vips_image_write( t[1], load->real ) ) 
 		return( -1 );

libvips/foreign/popplerload.c

@@ -76,6 +76,11 @@
 #include <cairo.h>
 #include <poppler.h>
 
+/* Render PDFs with tiles this size. They need to be pretty big to limit 
+ * overcomputation.
+ */
+#define TILE_SIZE (2000)
+
 #define VIPS_TYPE_FOREIGN_LOAD_PDF (vips_foreign_load_pdf_get_type())
 #define VIPS_FOREIGN_LOAD_PDF( obj ) \
 	(G_TYPE_CHECK_INSTANCE_CAST( (obj), \
@@ -495,14 +500,14 @@ vips_foreign_load_pdf_load( VipsForeignLoad *load )
 	g_signal_connect( t[0], "minimise",
 		G_CALLBACK( vips_foreign_load_pdf_minimise ), pdf );
 
-	/* Very large strips to limit render calls per page.
-	 */
 	vips_foreign_load_pdf_set_image( pdf, t[0] ); 
 	if( vips_image_generate( t[0], 
 		NULL, vips_foreign_load_pdf_generate, NULL, pdf, NULL ) ||
-		vips_sequential( t[0], &t[1],
+		vips_tilecache( t[0], &t[1],
-			"tile_height", VIPS_MIN( 5000, pdf->pages[0].height ), 
+			"tile_width", TILE_SIZE,
-			NULL ) || 
+			"tile_height", TILE_SIZE,
+			"max_tiles", 2 * (1 + t[0]->Xsize / TILE_SIZE),
+			NULL ) ||
 		vips_image_write( t[1], load->real ) ) 
 		return( -1 );
 

libvips/foreign/svgload.c

@@ -26,6 +26,8 @@
  * 	- allow utf-8 headers for svg detection
  * 28/4/22
  * 	- support rsvg_handle_get_intrinsic_size_in_pixels()
+ * 5/6/22
+ * 	- allow random access
  */
 
 /*
@@ -79,6 +81,11 @@
 #include <cairo.h>
 #include <librsvg/rsvg.h>
 
+/* Render SVGs with tiles this size. They need to be pretty big to limit 
+ * overcomputation.
+ */
+#define TILE_SIZE (2000)
+
 /* The <svg tag must appear within this many bytes of the start of the file.
  */
 #define SVG_HEADER_SIZE (1000)
@@ -310,13 +317,15 @@ vips_foreign_load_svg_dispose( GObject *gobject )
 static VipsForeignFlags
 vips_foreign_load_svg_get_flags_filename( const char *filename )
 {
-	return( VIPS_FOREIGN_SEQUENTIAL );
+	/* We can render any part of the page on demand.
+	 */
+	return( VIPS_FOREIGN_PARTIAL );
 }
 
 static VipsForeignFlags
 vips_foreign_load_svg_get_flags( VipsForeignLoad *load )
 {
-	return( VIPS_FOREIGN_SEQUENTIAL );
+	return( VIPS_FOREIGN_PARTIAL );
 }
 
 #if LIBRSVG_CHECK_VERSION( 2, 52, 0 )
@@ -658,21 +667,18 @@ vips_foreign_load_svg_load( VipsForeignLoad *load )
 	VipsImage **t = (VipsImage **) 
 		vips_object_local_array( (VipsObject *) load, 3 );
 
-	/* Make tiles 2000 pixels high to limit overcomputation. 
+	/* Enough tiles for two complete rows.
 	 */
 	t[0] = vips_image_new(); 
 	if( vips_foreign_load_svg_parse( svg, t[0] ) ||
 		vips_image_generate( t[0], NULL,
 			vips_foreign_load_svg_generate, NULL, svg, NULL ) ||
 		vips_tilecache( t[0], &t[1],
-			"tile_width", t[0]->Xsize,
+			"tile_width", TILE_SIZE,
-			"tile_height", 2000,
+			"tile_height", TILE_SIZE,
-			"max_tiles", 1,
+			"max_tiles", 2 * (1 + t[0]->Xsize / TILE_SIZE),
 			NULL ) ||
-		vips_sequential( t[1], &t[2], 
+		vips_image_write( t[1], load->real ) ) 
-			"tile_height", 2000, 
-			NULL ) ||
-		vips_image_write( t[2], load->real ) ) 
 		return( -1 );
 
 	return( 0 );