Add pasteImage and saveWebImage to Mapscript imageObj (MapServer#7015)

Follow-up and replacement to MapServer#6932 (thanks to @jbfrd)

src/mapscript/python/tests/cases/image_test.py

@@ -154,6 +154,37 @@ def testImageGetBytes(self):
             assert pyimg.size == (200, 200)
             assert pyimg.mode == "RGB"
 
+    def testSaveWebImage(self):
+        """save an image to the imagepath folder and return its URL"""
+
+        # set the imagepath and imageurl on the MAP WEB object
+        self.map.web.imagepath = ""
+        self.map.web.imageurl = "/output/"
+
+        image = self.map.draw()
+        url = image.saveWebImage()
+        assert url.startswith("/output/")
+        assert url.endswith(".png")
+
+    def testPasteImage(self):
+        """save an image to the imagepath folder and return its URL"""
+
+        image1 = self.map.draw()
+        image2 = self.map.draw()
+
+        ret = image1.pasteImage(image2, opacity=0.5, dstx=10, dsty=10)
+        assert ret == mapscript.MS_SUCCESS
+
+        filename = "testImagePaste.png"
+        fh = open(filename, "wb")
+        image1.write(fh)
+        fh.close()
+        if have_image:
+            pyimg = Image.open(filename)
+            assert pyimg.format == "PNG"
+            assert pyimg.size == (200, 200)
+            assert pyimg.mode == "RGB"
+
 
 if __name__ == "__main__":
     unittest.main()

src/mapscript/swiginc/image.i

@@ -196,4 +196,66 @@
         free(buffer.data);
         return size;
     }
+
+    /**
+    Pastes another imageObj on top of this imageObj.
+    If optional dstx,dsty are provided then they define the position where the
+    image should be copied (dstx,dsty = top-left corner position).
+    */
+    int pasteImage(imageObj *imageSrc, double opacity=1.0, int dstx=0, int dsty=0)
+    {
+        rendererVTableObj *renderer = NULL;
+        rasterBufferObj rb;
+
+        if (!MS_RENDERER_PLUGIN(self->format)) {
+            msSetError(MS_IMGERR, "PasteImage function should only be used with renderer plugin drivers.",
+                       "imageObj::pasteImage");
+            return MS_FAILURE;
+        }
+
+        memset(&rb,0,sizeof(rasterBufferObj));
+
+        renderer = self->format->vtable;
+        if(MS_SUCCESS != renderer->getRasterBufferHandle(imageSrc, &rb)) {
+            msSetError(MS_IMGERR, "PasteImage failed to extract rasterbuffer handle",
+                       "imageObj::pasteImage");
+            return MS_FAILURE;
+        }
+
+        if(MS_SUCCESS != renderer->mergeRasterBuffer(self, &rb, opacity, 0, 0, dstx, dsty, rb.width, rb.height)) {
+            msSetError(MS_IMGERR, "PasteImage failed to merge raster buffer",
+                       "imageObj::pasteImage");
+            return MS_FAILURE;
+        }
+
+        return MS_SUCCESS;
+
+    }
+
+    /**
+    Writes the image to temp directory.
+    Returns the image URL.
+    */
+    char *saveWebImage()
+    {
+        char *imageFile = NULL;
+        char *imageFilename = NULL;
+        char path[MS_MAXPATHLEN];
+        char *imageUrlFull = NULL;
+
+        imageFilename = msTmpFilename(self->format->extension);
+        imageFile = msBuildPath(path, self->imagepath, imageFilename);
+
+        if (msSaveImage(NULL, self, imageFile) != MS_SUCCESS) {
+            msSetError(MS_IMGERR, "Failed writing image to %s",
+                       "imageObj::saveWebImage",
+                       imageFile);
+            msFree(imageFilename);
+            return NULL;
+        }
+
+        imageUrlFull = msStrdup(msBuildPath(path, self->imageurl, imageFilename));
+        msFree(imageFilename);
+        return imageUrlFull;
+    }
 }