Add vips_image_get_gainmap

spec/meta_spec.lua

@@ -1,6 +1,7 @@
 local vips = require "vips"
 local ffi = require "ffi"
 
+local UHDR_FILE = "./spec/images/uhdr.jpg"
 -- test metadata read/write
 describe("metadata", function()
     local array, im
@@ -59,4 +60,28 @@ describe("metadata", function()
 
         assert.are.same(im2:format(), "double")
     end)
+
+    it("can set gainmap", function()
+        if vips.version.at_least(8, 18) and vips.has("uhdrload") then
+            local function crop_gainmap(image)
+                local gainmap = image:get_gainmap()
+
+                if gainmap then
+                    local new_gainmap = gainmap:crop(0, 0, 10, 10)
+                    image = image:copy()
+                    image:set_type(vips.gvalue.image_type, "gainmap", new_gainmap)
+                end
+
+                return image
+            end
+
+            local image = vips.Image.new_from_file(UHDR_FILE)
+            image = crop_gainmap(image)
+            local buf = image:write_to_buffer(".jpg")
+            local new_image = vips.Image.new_from_buffer(buf, "")
+            local new_gainmap = new_image:get_gainmap()
+
+            assert.are.same(new_gainmap:width(), 10)
+        end
+    end)
 end)

src/vips.lua

@@ -64,6 +64,13 @@ function vips.concurrency_get()
     return vips_lib.vips_concurrency_get()
 end
 
+function vips.type_find(basename, nickname)
+    return vips_lib.vips_type_find(basename, nickname)
+end
+
+function vips.has(name)
+    return vips.type_find("VipsOperation", name) ~= 0
+end
 -- for compat with 1.1-6, when these were misnamed
 vips.set_max = vips.cache_set_max
 vips.get_max = vips.cache_get_max

src/vips/Image_methods.lua

@@ -497,6 +497,16 @@ function Image_method:remove(name)
     return vips_lib.vips_image_remove(self.vimage, name) ~= 0
 end
 
+function Image_method:get_gainmap()
+    collectgarbage("stop")
+    local vimage = vips_lib.vips_image_get_gainmap(self.vimage)
+    if vimage == ffi.NULL then
+        return nil
+    end
+
+    collectgarbage("restart")
+    return Image.new(vimage)
+end
 -- standard header fields
 
 function Image_method:width()

src/vips/cdefs.lua

@@ -35,6 +35,8 @@ ffi.cdef [[
     GType vips_blend_mode_get_type (void);
     GType vips_band_format_get_type (void);
 
+    GType vips_type_find (const char *basename, const char *nickname);
+
     int vips_enum_from_nick (const char *domain,
         GType gtype, const char *str);
     const char *vips_enum_nick (GType gtype, int value);
@@ -166,6 +168,8 @@ ffi.cdef [[
         // opaque
     } VipsImage;
 
+    VipsImage *vips_image_get_gainmap(VipsImage *image);
+
     typedef struct _VipsConnection {
         VipsObject parent_instance;