revise help text for loaders

Hopefully to make it clearer and more consistent.

See https://github.com/libvips/libvips/discussions/2982

libvips/foreign/heifload.c

@@ -1065,14 +1065,14 @@ vips_foreign_load_heif_class_init( VipsForeignLoadHeifClass *class )
 
 	VIPS_ARG_INT( class, "page", 2,
 		_( "Page" ),
-		_( "Load this page from the file" ),
+		_( "First page to load" ),
 		VIPS_ARGUMENT_OPTIONAL_INPUT,
 		G_STRUCT_OFFSET( VipsForeignLoadHeif, page ),
 		0, 100000, 0 );
 
 	VIPS_ARG_INT( class, "n", 3,
 		_( "n" ),
-		_( "Load this many pages" ),
+		_( "Number of pages to load, -1 for all" ),
 		VIPS_ARGUMENT_OPTIONAL_INPUT,
 		G_STRUCT_OFFSET( VipsForeignLoadHeif, n ),
 		-1, 100000, 1 );

libvips/foreign/magick6load.c

@@ -130,13 +130,6 @@ vips_foreign_load_magick_class_init( VipsForeignLoadMagickClass *class )
 		vips_foreign_load_magick_get_flags_filename;
 	load_class->get_flags = vips_foreign_load_magick_get_flags;
 
-	VIPS_ARG_BOOL( class, "all_frames", 20, 
-		_( "All frames" ), 
-		_( "Read all frames from an image" ),
-		VIPS_ARGUMENT_OPTIONAL_INPUT | VIPS_ARGUMENT_DEPRECATED,
-		G_STRUCT_OFFSET( VipsForeignLoadMagick, all_frames ),
-		FALSE );
-
 	VIPS_ARG_STRING( class, "density", 21,
 		_( "Density" ),
 		_( "Canvas resolution for rendering vector formats like SVG" ),
@@ -146,17 +139,25 @@ vips_foreign_load_magick_class_init( VipsForeignLoadMagickClass *class )
 
 	VIPS_ARG_INT( class, "page", 22,
 		_( "Page" ),
-		_( "Load this page from the file" ),
+		_( "First page to load" ),
 		VIPS_ARGUMENT_OPTIONAL_INPUT,
 		G_STRUCT_OFFSET( VipsForeignLoadMagick, page ),
 		0, 100000, 0 );
 
 	VIPS_ARG_INT( class, "n", 23,
 		_( "n" ),
-		_( "Load this many pages" ),
+		_( "Number of pages to load, -1 for all" ),
 		VIPS_ARGUMENT_OPTIONAL_INPUT,
 		G_STRUCT_OFFSET( VipsForeignLoadMagick, n ),
 		-1, 100000, 1 );
+
+	VIPS_ARG_BOOL( class, "all_frames", 20, 
+		_( "All frames" ), 
+		_( "Read all frames from an image" ),
+		VIPS_ARGUMENT_OPTIONAL_INPUT | VIPS_ARGUMENT_DEPRECATED,
+		G_STRUCT_OFFSET( VipsForeignLoadMagick, all_frames ),
+		FALSE );
+
 }
 
 static void

libvips/foreign/magick7load.c

@@ -380,14 +380,14 @@ vips_foreign_load_magick7_class_init( VipsForeignLoadMagick7Class *class )
 
 	VIPS_ARG_INT( class, "page", 21,
 		_( "Page" ),
-		_( "Load this page from the file" ),
+		_( "First page to load" ),
 		VIPS_ARGUMENT_OPTIONAL_INPUT,
 		G_STRUCT_OFFSET( VipsForeignLoadMagick7, page ),
 		0, 100000, 0 );
 
 	VIPS_ARG_INT( class, "n", 22,
 		_( "n" ),
-		_( "Load this many pages" ),
+		_( "Number of pages to load, -1 for all" ),
 		VIPS_ARGUMENT_OPTIONAL_INPUT,
 		G_STRUCT_OFFSET( VipsForeignLoadMagick7, n ),
 		-1, 100000, 1 );
@@ -868,7 +868,8 @@ G_DEFINE_TYPE( VipsForeignLoadMagick7Buffer, vips_foreign_load_magick7_buffer,
 static gboolean
 vips_foreign_load_magick7_buffer_is_a_buffer( const void *buf, size_t len )
 {
-	return( len > 10 && magick_ismagick( (const unsigned char *) buf, len ) );
+	return( len > 10 && 
+                magick_ismagick( (const unsigned char *) buf, len ) );
 }
 
 static int

libvips/foreign/nsgifload.c

@@ -542,14 +542,14 @@ vips_foreign_load_nsgif_class_init( VipsForeignLoadNsgifClass *class )
 
 	VIPS_ARG_INT( class, "page", 10,
 		_( "Page" ),
-		_( "Load this page from the file" ),
+		_( "First page to load" ),
 		VIPS_ARGUMENT_OPTIONAL_INPUT,
 		G_STRUCT_OFFSET( VipsForeignLoadNsgif, page ),
 		0, 100000, 0 );
 
 	VIPS_ARG_INT( class, "n", 6,
 		_( "n" ),
-		_( "Load this many pages" ),
+		_( "Number of pages to load, -1 for all" ),
 		VIPS_ARGUMENT_OPTIONAL_INPUT,
 		G_STRUCT_OFFSET( VipsForeignLoadNsgif, n ),
 		-1, 100000, 1 );

libvips/foreign/pdfiumload.c

@@ -689,42 +689,42 @@ vips_foreign_load_pdf_class_init( VipsForeignLoadPdfClass *class )
 
 	VIPS_ARG_INT( class, "page", 10,
 		_( "Page" ),
-		_( "Load this page from the file" ),
+		_( "First page to load" ),
 		VIPS_ARGUMENT_OPTIONAL_INPUT,
 		G_STRUCT_OFFSET( VipsForeignLoadPdf, page_no ),
 		0, 100000, 0 );
 
 	VIPS_ARG_INT( class, "n", 11,
 		_( "n" ),
-		_( "Load this many pages" ),
+		_( "Number of pages to load, -1 for all" ),
 		VIPS_ARGUMENT_OPTIONAL_INPUT,
 		G_STRUCT_OFFSET( VipsForeignLoadPdf, n ),
 		-1, 100000, 1 );
 
 	VIPS_ARG_DOUBLE( class, "dpi", 12,
 		_( "DPI" ),
-		_( "Render at this DPI" ),
+		_( "DPI to render at" ),
 		VIPS_ARGUMENT_OPTIONAL_INPUT,
 		G_STRUCT_OFFSET( VipsForeignLoadPdf, dpi ),
 		0.001, 100000.0, 72.0 );
 
 	VIPS_ARG_DOUBLE( class, "scale", 13,
 		_( "Scale" ),
-		_( "Scale output by this factor" ),
+		_( "Factor to scale by" ),
 		VIPS_ARGUMENT_OPTIONAL_INPUT,
 		G_STRUCT_OFFSET( VipsForeignLoadPdf, scale ),
 		0.001, 100000.0, 1.0 );
 
 	VIPS_ARG_BOXED( class, "background", 14, 
 		_( "Background" ), 
-		_( "Background value" ),
+		_( "Background colour" ),
 		VIPS_ARGUMENT_OPTIONAL_INPUT,
 		G_STRUCT_OFFSET( VipsForeignLoadPdf, background ),
 		VIPS_TYPE_ARRAY_DOUBLE );
 
 	VIPS_ARG_STRING( class, "password", 25, 
 		_( "Password" ), 
-		_( "Decrypt with this password" ),
+		_( "Password to decrypt with" ),
 		VIPS_ARGUMENT_OPTIONAL_INPUT,
 		G_STRUCT_OFFSET( VipsForeignLoadPdf, password ),
 		NULL );

libvips/foreign/popplerload.c

@@ -542,42 +542,42 @@ vips_foreign_load_pdf_class_init( VipsForeignLoadPdfClass *class )
 
 	VIPS_ARG_INT( class, "page", 20,
 		_( "Page" ),
-		_( "Load this page from the file" ),
+		_( "First page to load" ),
 		VIPS_ARGUMENT_OPTIONAL_INPUT,
 		G_STRUCT_OFFSET( VipsForeignLoadPdf, page_no ),
 		0, 100000, 0 );
 
 	VIPS_ARG_INT( class, "n", 21,
 		_( "n" ),
-		_( "Load this many pages" ),
+		_( "Number of pages to load, -1 for all" ),
 		VIPS_ARGUMENT_OPTIONAL_INPUT,
 		G_STRUCT_OFFSET( VipsForeignLoadPdf, n ),
 		-1, 100000, 1 );
 
 	VIPS_ARG_DOUBLE( class, "dpi", 22,
 		_( "DPI" ),
-		_( "Render at this DPI" ),
+		_( "DPI to render at" ),
 		VIPS_ARGUMENT_OPTIONAL_INPUT,
 		G_STRUCT_OFFSET( VipsForeignLoadPdf, dpi ),
 		0.001, 100000.0, 72.0 );
 
 	VIPS_ARG_DOUBLE( class, "scale", 23,
 		_( "Scale" ),
-		_( "Scale output by this factor" ),
+		_( "Factor to scale by" ),
 		VIPS_ARGUMENT_OPTIONAL_INPUT,
 		G_STRUCT_OFFSET( VipsForeignLoadPdf, scale ),
 		0.001, 100000.0, 1.0 );
 
 	VIPS_ARG_BOXED( class, "background", 24, 
 		_( "Background" ), 
-		_( "Background value" ),
+		_( "Background colour" ),
 		VIPS_ARGUMENT_OPTIONAL_INPUT,
 		G_STRUCT_OFFSET( VipsForeignLoadPdf, background ),
 		VIPS_TYPE_ARRAY_DOUBLE );
 
 	VIPS_ARG_STRING( class, "password", 25, 
 		_( "Password" ), 
-		_( "Decrypt with this password" ),
+		_( "Password to decrypt with" ),
 		VIPS_ARGUMENT_OPTIONAL_INPUT,
 		G_STRUCT_OFFSET( VipsForeignLoadPdf, password ),
 		NULL );

libvips/foreign/tiffload.c

@@ -191,14 +191,14 @@ vips_foreign_load_tiff_class_init( VipsForeignLoadTiffClass *class )
 
 	VIPS_ARG_INT( class, "page", 20, 
 		_( "Page" ), 
-		_( "Load this page from the image" ),
+		_( "First page to load" ),
 		VIPS_ARGUMENT_OPTIONAL_INPUT,
 		G_STRUCT_OFFSET( VipsForeignLoadTiff, page ),
 		0, 100000, 0 );
 
 	VIPS_ARG_INT( class, "n", 21,
 		_( "n" ),
-		_( "Load this many pages" ),
+		_( "Number of pages to load, -1 for all" ),
 		VIPS_ARGUMENT_OPTIONAL_INPUT,
 		G_STRUCT_OFFSET( VipsForeignLoadTiff, n ),
 		-1, 100000, 1 );
@@ -212,7 +212,7 @@ vips_foreign_load_tiff_class_init( VipsForeignLoadTiffClass *class )
 
 	VIPS_ARG_INT( class, "subifd", 21,
 		_( "subifd" ),
-		_( "Select subifd index" ),
+		_( "Subifd index" ),
 		VIPS_ARGUMENT_OPTIONAL_INPUT,
 		G_STRUCT_OFFSET( VipsForeignLoadTiff, subifd ),
 		-1, 100000, -1 );

libvips/foreign/webpload.c

@@ -178,28 +178,25 @@ vips_foreign_load_webp_class_init( VipsForeignLoadWebpClass *class )
 
 	VIPS_ARG_INT( class, "page", 20,
 		_( "Page" ),
-		_( "Load this page from the file" ),
+		_( "First page to load" ),
 		VIPS_ARGUMENT_OPTIONAL_INPUT,
 		G_STRUCT_OFFSET( VipsForeignLoadWebp, page ),
 		0, 100000, 0 );
 
 	VIPS_ARG_INT( class, "n", 21,
 		_( "n" ),
-		_( "Load this many pages" ),
+		_( "Number of pages to load, -1 for all" ),
 		VIPS_ARGUMENT_OPTIONAL_INPUT,
 		G_STRUCT_OFFSET( VipsForeignLoadWebp, n ),
 		-1, 100000, 1 );
 
 	VIPS_ARG_DOUBLE( class, "scale", 22, 
 		_( "Scale" ), 
-		_( "Scale factor on load" ),
+		_( "Factor to scale by" ),
 		VIPS_ARGUMENT_OPTIONAL_INPUT,
 		G_STRUCT_OFFSET( VipsForeignLoadWebp, scale ),
 		0.0, 1024.0, 1.0 );
 
-	/* Old and deprecated scaling API. A float param lets do
-	 * shrink-on-load for thumbnail faster and more accurately.
-	 */
 	VIPS_ARG_INT( class, "shrink", 23, 
 		_( "Shrink" ), 
 		_( "Shrink factor on load" ),