rubycdp · route · Sep 26, 2023 · Sep 24, 2023 · Sep 26, 2023
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -2,6 +2,7 @@
 
 ### Added
 - `Ferrum::Page#disable_javascript` disables the JavaScript from the HTML source
+- `Ferrum::Page#set_viewport` emulates the viewport
 
 ### Changed
 

diff --git a/README.md b/README.md
@@ -922,6 +922,21 @@ browser.disable_javascript
 ```
 
 
+#### set_viewport
+
+Overrides device screen dimensions and emulates viewport.
+
+* options `Hash`
+  * :width `Integer`, viewport width. `0` by default
+  * :height `Integer`, viewport height. `0` by default
+  * :scale_factor `Float`, device scale factor. `0` by default
+  * :mobile `Boolean`, whether to emulate mobile device. `false` by default
+
+```ruby
+browser.set_viewport(width: 1000, height: 600, scale_factor: 3)
+```
+
+
 ## Frames
 
 #### frames : `Array[Frame] | []`

diff --git a/lib/ferrum/browser.rb b/lib/ferrum/browser.rb
@@ -28,7 +28,7 @@ class Browser
                 add_script_tag add_style_tag bypass_csp
                 on position position=
                 playback_rate playback_rate=
-                disable_javascript] => :page
+                disable_javascript set_viewport] => :page
     delegate %i[default_user_agent] => :process
 
     attr_reader :client, :process, :contexts, :options, :window_size, :base_url

diff --git a/lib/ferrum/page.rb b/lib/ferrum/page.rb
@@ -133,6 +133,30 @@ def close
       @client.close
     end
 
+    #
+    # Overrides device screen dimensions and emulates viewport according to parameters
+    #
+    # Read more [here](https://chromedevtools.github.io/devtools-protocol/tot/Emulation/#method-setDeviceMetricsOverride).
+    #
+    # @param [Integer] width width value in pixels. 0 disables the override
+    #
+    # @param [Integer] height height value in pixels. 0 disables the override
+    #
+    # @param [Float] scale_factor device scale factor value. 0 disables the override
+    #
+    # @param [Boolean] mobile whether to emulate mobile device
+    #
+    def set_viewport(width:, height:, scale_factor: 0, mobile: false)
+      command(
+        "Emulation.setDeviceMetricsOverride",
+        slowmoable: true,
+        width: width,
+        height: height,
+        deviceScaleFactor: scale_factor,
+        mobile: mobile
+      )
+    end
+
     def resize(width: nil, height: nil, fullscreen: false)
       if fullscreen
         width, height = document_size
@@ -142,11 +166,7 @@ def resize(width: nil, height: nil, fullscreen: false)
         set_window_bounds(width: width, height: height)
       end
 
-      command("Emulation.setDeviceMetricsOverride", slowmoable: true,
-                                                    width: width,
-                                                    height: height,
-                                                    deviceScaleFactor: 0,
-                                                    mobile: false)
+      set_viewport(width: width, height: height)
     end
 
     #

diff --git a/spec/page_spec.rb b/spec/page_spec.rb
@@ -186,4 +186,13 @@
       expect(page.main_frame.body).to eq("<html><head></head><body><p>text</p></body></html>")
     end
   end
+
+  describe "#set_viewport" do
+    it "overrides the viewport size" do
+      page.set_viewport(width: 500, height: 300, scale_factor: 2)
+
+      expect(page.viewport_size).to eq([500, 300])
+      expect(page.device_pixel_ratio).to eq(2)
+    end
+  end
 end
diff --git a/spec/support/views/initial_alert.erb b/spec/support/views/initial_alert.erb