Add speechbubble alpha option

commands/image-editing/speechbubble.js

@@ -1,12 +1,25 @@
 import ImageCommand from "../../classes/imageCommand.js";
 
 class SpeechBubbleCommand extends ImageCommand {
-  params = {
+  params() {
-    water: "assets/images/speechbubble.png",
+    return {
-    gravity: "north",
+      water: this.specialArgs.alpha ? "assets/images/speech.png" : "assets/images/speechbubble.png",
-    resize: true,
+      gravity: "north",
-    yscale: 0.2,
+      resize: true,
-  };
+      yscale: 0.2,
+      alpha: this.specialArgs.alpha
+    };
+  }
+
+  static init() {
+    super.init();
+    this.flags.push({
+      name: "alpha",
+      description: "Make the top of the speech bubble transparent",
+      type: 5
+    });
+    return this;
+  }
 
   static description = "Adds a speech bubble to an image";
   static aliases = ["speech", "sb"];

natives/watermark.cc

@@ -22,6 +22,8 @@ Napi::Value Watermark(const Napi::CallbackInfo &info) {
     bool append = obj.Has("append")
                       ? obj.Get("append").As<Napi::Boolean>().Value()
                       : false;
+    bool alpha =
+        obj.Has("alpha") ? obj.Get("alpha").As<Napi::Boolean>().Value() : false;
     bool mc = obj.Has("mc") ? obj.Get("mc").As<Napi::Boolean>().Value() : false;
     string basePath = obj.Get("basePath").As<Napi::String>().Utf8Value();
     string type = obj.Get("type").As<Napi::String>().Utf8Value();
@@ -55,8 +57,40 @@ Napi::Value Watermark(const Napi::CallbackInfo &info) {
           watermark.resize((double)page_height / (double)watermark.height());
     }
 
+    int x = 0, y = 0;
+    switch (gravity) {
+      case 1:
+        break;
+      case 2:
+        x = (width / 2) - (watermark.width() / 2);
+        break;
+      case 3:
+        x = width - watermark.width();
+        break;
+      case 5:
+        x = (width / 2) - (watermark.width() / 2);
+        y = (page_height / 2) - (watermark.height() / 2);
+        break;
+      case 6:
+        x = width - watermark.width();
+        y = (page_height / 2) - (watermark.height() / 2);
+        break;
+      case 8:
+        x = (width / 2) - (watermark.width() / 2);
+        y = page_height - watermark.height();
+        break;
+      case 9:
+        x = width - watermark.width();
+        y = page_height - watermark.height();
+        break;
+    }
+
     vector<VImage> img;
     int addedHeight = 0;
+    VImage contentAlpha;
+    VImage frameAlpha;
+    VImage bg;
+    VImage frame;
     for (int i = 0; i < n_pages; i++) {
       VImage img_frame =
           type == "gif" ? in.crop(0, i * page_height, width, page_height) : in;
@@ -77,36 +111,35 @@ Napi::Value Watermark(const Napi::CallbackInfo &info) {
         addedHeight = 15;
         img.push_back(composited);
       } else {
-        int x = 0, y = 0;
+        VImage composited;
-        switch (gravity) {
+        if (alpha) {
-          case 1:
+          if (i == 0) {
-            break;
+            contentAlpha = watermark.extract_band(0).embed(
-          case 2:
+                x, y, width, page_height,
-            x = (width / 2) - (watermark.width() / 2);
+                VImage::option()->set("extend", "white"));
-            break;
+            frameAlpha = watermark.extract_band(1).embed(
-          case 3:
+                x, y, width, page_height,
-            x = width - watermark.width();
+                VImage::option()->set("extend", "black"));
-            break;
+            bg =
-          case 5:
+                frameAlpha.new_from_image({0, 0, 0}).copy(VImage::option()->set(
-            x = (width / 2) - (watermark.width() / 2);
+                    "interpretation", VIPS_INTERPRETATION_sRGB));
-            y = (page_height / 2) - (watermark.height() / 2);
+            frame = bg.bandjoin(frameAlpha);
-            break;
+            if (type == "jpg" || type == "jpeg") {
-          case 6:
+              type = "png";
-            x = width - watermark.width();
+            }
-            y = (page_height / 2) - (watermark.height() / 2);
+          }
-            break;
+          VImage content =
-          case 8:
+              img_frame.extract_band(0, VImage::option()->set("n", 3))
-            x = (width / 2) - (watermark.width() / 2);
+                  .bandjoin(contentAlpha & img_frame.extract_band(3));
-            y = page_height - watermark.height();
+
-            break;
+          composited =
-          case 9:
+              content.composite2(frame, VIPS_BLEND_MODE_OVER,
-            x = width - watermark.width();
-            y = page_height - watermark.height();
-            break;
-        }
-        VImage composited =
-            img_frame.composite2(watermark, VIPS_BLEND_MODE_OVER,
                                  VImage::option()->set("x", x)->set("y", y));
+        } else {
+          composited =
+              img_frame.composite2(watermark, VIPS_BLEND_MODE_OVER,
+                                   VImage::option()->set("x", x)->set("y", y));
+        }
         img.push_back(composited);
       }
     }