improve display of computed multipage images

Author: jcupitt

CHANGELOG.md

@@ -7,6 +7,7 @@
 - add `vips8_xxxxx` builtins, remove `vips_call9`
 - improve search and display of builtins
 - add `vips_image_guess_interpretation` builtin
+- improve display of computed multipage images
 
 ## 9.0.13 2025/09/20
 

TODO

@@ -1,3 +1,6 @@
+- try < > in the image titlebar
+
+    seems to get stuck on eg. mp3 files
 
 - toolkitgroupview could have a non-scrolling version as the default
 

src/tilesource.c

@@ -136,7 +136,8 @@ typedef struct _TilesourceUpdate {
 	int z;
 } TilesourceUpdate;
 
-/* Open a specified level. Take page (if relevant) from the tilesource.
+/* Open a specified level. Take page (if relevant) from the tilesource. Try to
+ * open all pages if pages_same_size is set.
  */
 static VipsImage *
 tilesource_open(Tilesource *tilesource, int level)
@@ -145,7 +146,7 @@ tilesource_open(Tilesource *tilesource, int level)
 	 * images, since pages can vary in size (eg. PDF or TIFF) and we can't
 	 * open everything.
 	 */
-	gboolean all_pages = tilesource->type == TILESOURCE_TYPE_TOILET_ROLL;
+	gboolean all_pages = tilesource->pages_same_size;
 	int n = all_pages ? -1 : 1;
 	int page = all_pages ? 0 : tilesource->page;
 
@@ -310,7 +311,7 @@ tilesource_image(Tilesource *tilesource, VipsImage **mask_out, int current_z)
 
 	/* Open the image with any shrink-on-load tricks.
 	 */
-	if (tilesource->type == TILESOURCE_TYPE_IMAGE) {
+	if (!tilesource->filename) {
 		/* We are displaying a VipsImage* and there's no reopen possible.
 		 */
 		image = tilesource->base;
@@ -369,13 +370,13 @@ tilesource_image(Tilesource *tilesource, VipsImage **mask_out, int current_z)
 	printf("\timage_height = %d\n", tilesource->image_height);
 #endif /*DEBUG*/
 
-	/* If we have a toilet roll source and we are displaying multipage or
+	/* If we have a pages-same-size source and we are displaying multipage or
 	 * animated, crop out the page we want.
 	 *
 	 * We need to crop using the page size on image, since it might have
 	 * been shrunk by shrink-on-load above ^^
 	 */
-	if (tilesource->type == TILESOURCE_TYPE_TOILET_ROLL &&
+	if (tilesource->pages_same_size &&
 		(tilesource->mode == TILESOURCE_MODE_MULTIPAGE ||
 		 tilesource->mode == TILESOURCE_MODE_ANIMATED)) {
 		// loaders will adjust page_height for shrink-on-load, so we can just
@@ -385,8 +386,7 @@ tilesource_image(Tilesource *tilesource, VipsImage **mask_out, int current_z)
 		VipsImage *x;
 
 		if (vips_crop(image, &x,
-				0, tilesource->page * page_height,
-				image->Xsize, page_height, NULL))
+			0, tilesource->page * page_height, image->Xsize, page_height, NULL))
 			return NULL;
 		VIPS_UNREF(image);
 		image = x;
@@ -403,7 +403,7 @@ tilesource_image(Tilesource *tilesource, VipsImage **mask_out, int current_z)
 
 	/* In pages-as-bands mode, crop out all pages and join band-wise.
 	 */
-	if (tilesource->type == TILESOURCE_TYPE_TOILET_ROLL &&
+	if (tilesource->pages_same_size &&
 		tilesource->mode == TILESOURCE_MODE_PAGES_AS_BANDS) {
 		// loaders will adjust page_height for shrink-on-load, so we can just
 		// use that
@@ -504,7 +504,7 @@ tilesource_image(Tilesource *tilesource, VipsImage **mask_out, int current_z)
 		*mask_out = NULL;
 	}
 	else {
-		/* Need something to track the z at which we made this sink_screen.
+		/* Need to track the z at which we made this sink_screen.
 		 */
 		TilesourceUpdate *update = VIPS_NEW(image, TilesourceUpdate);
 		update->tilesource = tilesource;
@@ -1425,8 +1425,6 @@ tilesource_print(Tilesource *tilesource)
 	int i;
 
 	printf("tilesource: %p\n", tilesource);
-	printf("\ttype = %s\n",
-		vips_enum_nick(TILESOURCE_TYPE_TYPE, tilesource->type));
 	printf("\tloader = %s\n", tilesource->loader);
 	printf("\tn_pages = %d\n", tilesource->n_pages);
 	printf("\tpage_height = %d\n", tilesource->page_height);
@@ -1490,8 +1488,7 @@ tilesource_default_mode(Tilesource *tilesource)
 {
 	TilesourceMode mode;
 
-	if (tilesource->type == TILESOURCE_TYPE_TOILET_ROLL &&
-		tilesource->n_pages > 1) {
+	if (tilesource->n_pages > 1) {
 		if (tilesource->delay)
 			mode = TILESOURCE_MODE_ANIMATED;
 		else if (tilesource->all_mono)
@@ -1517,8 +1514,6 @@ tilesource_new_from_image(VipsImage *image)
 	if (tilesource_set_base(tilesource, image))
 		return NULL;
 
-	tilesource->type = TILESOURCE_TYPE_IMAGE;
-
 	tilesource->level_count = 1;
 	tilesource->level_width[0] = image->Xsize;;
 	tilesource->level_height[0] = image->Ysize;;
@@ -1530,13 +1525,17 @@ tilesource_new_from_image(VipsImage *image)
 	/* Sanity-check and set up the page geometry.
 	 */
 	tilesource->page_height = vips_image_get_page_height(image);
-	if (image->Ysize % tilesource->page_height == 0)
+	if (image->Ysize % tilesource->page_height == 0) {
 		tilesource->n_pages = image->Ysize / tilesource->page_height;
+		tilesource->pages_same_size = TRUE;
+	}
 	else {
 		tilesource->page_height = image->Ysize;
 		tilesource->n_pages = 1;
 	}
 
+	tilesource->all_mono = image->Bands == 1;
+
 	tilesource_default_mode(tilesource);
 
 	if (tilesource->mode == TILESOURCE_MODE_TOILET_ROLL)
@@ -1871,18 +1870,16 @@ tilesource_new_from_file(const char *filename)
 	/* Block error messages from eg. page-pyramidal TIFFs where pages
 	 * are not all the same size.
 	 */
-	tilesource->type = TILESOURCE_TYPE_TOILET_ROLL;
+	tilesource->pages_same_size = TRUE;
 	vips_error_freeze();
 	g_autoptr(VipsImage) x = tilesource_open(tilesource, 0);
 	vips_error_thaw();
 	if (x) {
-		/* Toilet-roll mode worked. We can update n_pages.
+		/* All pages worked. We can update n_pages.
 		 */
 		tilesource->page_height = vips_image_get_page_height(x);
-		if (x->Ysize % tilesource->page_height == 0) {
+		if (x->Ysize % tilesource->page_height == 0)
 			tilesource->n_pages = x->Ysize / tilesource->page_height;
-			tilesource->pages_same_size = TRUE;
-		}
 		else {
 #ifdef DEBUG
 			printf("tilesource_new_from_file: bad page layout\n");
@@ -1891,8 +1888,11 @@ tilesource_new_from_file(const char *filename)
 			tilesource->n_pages = 1;
 			VIPS_FREE(tilesource->delay);
 			tilesource->n_delay = 0;
+			tilesource->pages_same_size = FALSE;
 		}
 	}
+	else
+		tilesource->pages_same_size = FALSE;
 
 	/* Are all pages the same size and format, and also all mono (one
 	 * band)? We can display pages-as-bands.
@@ -1920,17 +1920,6 @@ tilesource_new_from_file(const char *filename)
 			tilesource->page_pyramid = FALSE;
 	}
 
-	/* Sniffing is done ... set the image type.
-	 */
-	if (tilesource->pages_same_size)
-		tilesource->type = TILESOURCE_TYPE_TOILET_ROLL;
-	else {
-		if (tilesource->page_pyramid)
-			tilesource->type = TILESOURCE_TYPE_PAGE_PYRAMID;
-		else
-			tilesource->type = TILESOURCE_TYPE_MULTIPAGE;
-	}
-
 	/* And now we can reopen in the correct mode.
 	 */
 	g_autoptr(VipsImage) base = tilesource_open(tilesource, 0);

src/tilesource.h

@@ -42,38 +42,6 @@
 #define TILESOURCE_GET_CLASS(obj) \
 	(G_TYPE_INSTANCE_GET_CLASS((obj), TILESOURCE_TYPE, TilesourceClass))
 
-/* The three basic types of image we support.
- *
- * MULTIPAGE
- *
- *	Pages differ in size or perhaps format, so must be loaded as separate
- *	images. Pages can have subifd pyramids. Includes single-page images.
- *	Reload on page change.
- *
- * PAGE_PYRAMID
- *
- *	"page" param is pyr levels. We load a single page and reload on
- *	magnification change.
- *
- * TOILET_ROLL
- *
- *	All pages are the identical, so we open as a single, tall, thin strip
- *	and the viewer does any presenting as pages / animation / etc. during
- *	conversion to image image.
- *
- *	These images can have subifd pyramids.
- *
- * IMAGE
- *
- *  We've been given a VipsImage* to display, held in @base.
- */
-typedef enum _TilesourceType {
-	TILESOURCE_TYPE_MULTIPAGE,
-	TILESOURCE_TYPE_PAGE_PYRAMID,
-	TILESOURCE_TYPE_TOILET_ROLL,
-	TILESOURCE_TYPE_IMAGE,
-} TilesourceType;
-
 /* The modes of image display we support.
  *
  * UNSET
@@ -87,18 +55,18 @@ typedef enum _TilesourceType {
  *
  * MULTIPAGE
  *
- *	Behaviour depends on TilesourceType:
+ *	Behaviour depends on Tilesource details:
  *
- *	TILESOURCE_TYPE_PAGE_PYRAMID
+ *	->page_pyramid
  *
  *		Disable page controls. No crop. Reload on mag change.
  *
- *	TILESOURCE_TYPE_TOILET_ROLL
+ *	->pages_same_size && ->delay && ->n_pages > 1
  *
- *		Enable page control iff > 1 page. Crop in display conversion
+ *		Enable page controls, crop in display conversion
  *		to select page.
  *
- *	TILESOURCE_TYPE_MULTIPAGE
+ *	->n_pages > 1
  *
  *		Enable page control iff > 1 page.
  *
@@ -149,6 +117,8 @@ typedef struct _Tilesource {
 	/* The loader and the file we have loaded from. We may need to reload
 	 * on a zoom or page change. We can't use a VipsSource since they are not
 	 * cached and we'd get repeated decode on page change.
+	 *
+	 * filename is NULL for a computed image.
 	 */
 	const char *loader;
 	char *filename;
@@ -159,7 +129,6 @@ typedef struct _Tilesource {
 	 * Some properties of this base image
 	 */
 	VipsImage *base;
-	TilesourceType type;			// what general type of image we have
 	int n_pages;
 	int page_height;
 	int n_subifds;
@@ -174,8 +143,8 @@ typedef struct _Tilesource {
 	 */
 	gboolean page_pyramid;
 
-	/* If all the pages are the same size and format, we can load as a
-	 * toilet roll.
+	/* If all the pages are the same size and format, we can display as a
+	 * toilet roll or animated.
 	 */
 	gboolean pages_same_size;