Transparency (#164)

* Add transparency field to WindowOptions

* Add transparency example

* Implement transparency on Wayland

* Improvements

* [WIP] X11 transparency

* Restructure

* Redox implement transparency

* Update src/lib.rs

Co-Authored-By: Cole Helbling <cole.e.helbling@outlook.com>

* Rust-2018 changes

* Fixed issue

* cargo fmt

* [WIP] Implement alpha transparency for windows

* Staging Windows code

* Transparency is currently unimplemented on Windows

* Add note

* Dont use assertions

* Correction

Co-authored-by: Antonino Siena <a.siena@gmx.de>
Co-authored-by: Cole Helbling <cole.e.helbling@outlook.com>

examples/image.rs

@@ -1,6 +1,3 @@
-extern crate minifb;
-extern crate png;
-
 use minifb::{Key, ScaleMode, Window, WindowOptions};
 
 fn main() {

examples/julia.rs

@@ -1,5 +1,3 @@
-extern crate minifb;
-
 use minifb::{Key, Scale, ScaleMode, Window, WindowOptions};
 
 const WIDTH: usize = 100;

examples/menu.rs

@@ -1,5 +1,3 @@
-extern crate minifb;
-
 use minifb::MENU_KEY_CTRL;
 use minifb::{InputCallback, Key, Menu, Scale, Window, WindowOptions};
 

examples/mouse.rs

@@ -1,5 +1,3 @@
-extern crate minifb;
-
 use minifb::{Key, MouseButton, MouseMode, Scale, Window, WindowOptions};
 
 const WIDTH: usize = 640;

examples/multi.rs

@@ -1,5 +1,3 @@
-extern crate minifb;
-
 use minifb::{Key, Scale, Window, WindowOptions};
 
 fn main() {

examples/noise.rs

@@ -1,5 +1,3 @@
-extern crate minifb;
-
 use minifb::{Key, ScaleMode, Window, WindowOptions};
 
 const WIDTH: usize = 640 / 2;

examples/title_cursor.rs

@@ -1,5 +1,3 @@
-extern crate minifb;
-
 use minifb::{CursorStyle, Key, MouseMode, Scale, Window, WindowOptions};
 
 const WIDTH: usize = 640;

examples/transparent.rs

@@ -0,0 +1,24 @@
+use minifb::{Key, ScaleMode, Window, WindowOptions};
+
+fn main() {
+    // Allocate the output buffer.
+    let buf = vec![0x00AAFF33; 320 * 480];
+
+    let mut window = Window::new(
+        "Press ESC to exit",
+        320,
+        480,
+        WindowOptions {
+            resize: true,
+            scale_mode: ScaleMode::Center,
+            borderless: true,
+            transparency: true,
+            ..WindowOptions::default()
+        },
+    )
+    .expect("Unable to open Window");
+
+    while window.is_open() && !window.is_key_down(Key::Escape) {
+        window.update_with_buffer(&buf, 320, 480).unwrap();
+    }
+}

src/lib.rs

@@ -187,6 +187,10 @@ pub struct WindowOptions {
     pub scale_mode: ScaleMode,
     /// Should the window be the topmost window (default: false)
     pub topmost: bool,
+    /// Specifies whether or not the window is allowed to draw transparent pixels (default: false)
+    /// Requires borderless to be 'true'
+    /// TODO: Currently not implemented on Windows and OSX
+    pub transparency: bool,
 }
 
 impl Window {
@@ -220,6 +224,11 @@ impl Window {
     ///  .expect("Unable to open Window");
     /// ```
     pub fn new(name: &str, width: usize, height: usize, opts: WindowOptions) -> Result<Window> {
+        if opts.transparency && !opts.borderless {
+            return Err(Error::WindowCreate(
+                "Window transparency requires the borderless property".to_owned(),
+            ));
+        }
         imp::Window::new(name, width, height, opts).map(Window)
     }
 
@@ -993,6 +1002,7 @@ impl Default for WindowOptions {
     fn default() -> WindowOptions {
         WindowOptions {
             borderless: false,
+            transparency: false,
             title: true,
             resize: false,
             scale: Scale::X1,

src/os/redox/mod.rs

@@ -67,6 +67,9 @@ impl Window {
         if !opts.title {
             window_flags.push(orbclient::WindowFlag::Borderless);
         }
+        if opts.transparency {
+            window_flags.push(orbclient::WindowFlag::Transparent);
+        }
 
         let window_opt =
             orbclient::Window::new_flags(-1, -1, window_width, window_height, name, &window_flags);

src/os/unix/wayland.rs

@@ -520,7 +520,7 @@ impl Window {
 
         let (display, input) = DisplayInfo::new(
             (width as i32 * scale, height as i32 * scale),
-            false,
+            opts.transparency,
             !opts.borderless,
         )?;
 

src/os/unix/x11.rs

@@ -99,8 +99,8 @@ struct DisplayInfo {
 }
 
 impl DisplayInfo {
-    fn new() -> Result<DisplayInfo> {
+    fn new(transparency: bool) -> Result<DisplayInfo> {
-        let mut display = Self::setup()?;
+        let mut display = Self::setup(transparency)?;
 
         display.check_formats()?;
         display.check_extensions()?;
@@ -110,7 +110,7 @@ impl DisplayInfo {
         Ok(display)
     }
 
-    fn setup() -> Result<DisplayInfo> {
+    fn setup(transparency: bool) -> Result<DisplayInfo> {
         unsafe {
             let lib = xlib::Xlib::open()
                 .map_err(|e| Error::WindowCreate(format!("failed to load Xlib: {:?}", e)))?;
@@ -124,10 +124,29 @@ impl DisplayInfo {
                 return Err(Error::WindowCreate("XOpenDisplay failed".to_owned()));
             }
 
-            let screen = (lib.XDefaultScreen)(display);
+            let screen;
-            let visual = (lib.XDefaultVisual)(display, screen);
+            let visual;
+            let depth;
+
+            let mut vinfo: xlib::XVisualInfo = std::mem::zeroed();
+            if transparency {
+                (lib.XMatchVisualInfo)(
+                    display,
+                    (lib.XDefaultScreen)(display),
+                    32,
+                    xlib::TrueColor,
+                    &mut vinfo as *mut _,
+                );
+                screen = vinfo.screen;
+                visual = vinfo.visual;
+                depth = vinfo.depth;
+            } else {
+                screen = (lib.XDefaultScreen)(display);
+                visual = (lib.XDefaultVisual)(display, screen);
+                depth = (lib.XDefaultDepth)(display, screen);
+            }
+
             let gc = (lib.XDefaultGC)(display, screen);
-            let depth = (lib.XDefaultDepth)(display, screen);
 
             let screen_width = cast::usize((lib.XDisplayWidth)(display, screen))
                 .map_err(|e| Error::WindowCreate(format!("illegal width: {}", e)))?;
@@ -316,7 +335,7 @@ impl Window {
         // FIXME: this DisplayInfo should be a singleton, hence this code
         // is probably no good when using multiple windows.
 
-        let mut d = DisplayInfo::new()?;
+        let mut d = DisplayInfo::new(opts.transparency)?;
 
         let scale =
             Self::get_scale_factor(width, height, d.screen_width, d.screen_height, opts.scale);
@@ -331,6 +350,10 @@ impl Window {
 
             attributes.border_pixel = (d.lib.XBlackPixel)(d.display, d.screen);
             attributes.background_pixel = attributes.border_pixel;
+            if opts.transparency {
+                attributes.colormap =
+                    (d.lib.XCreateColormap)(d.display, root, d.visual, xlib::AllocNone);
+            }
 
             attributes.backing_store = xlib::NotUseful;
 
@@ -356,10 +379,12 @@ impl Window {
                 d.depth,
                 xlib::InputOutput as u32, /* class */
                 d.visual,
-                xlib::CWBackingStore | xlib::CWBackPixel | xlib::CWBorderPixel,
+                xlib::CWColormap | xlib::CWBackingStore | xlib::CWBackPixel | xlib::CWBorderPixel,
                 &mut attributes,
             );
 
+            d.gc = (d.lib.XCreateGC)(d.display, handle, 0, ptr::null_mut());
+
             if handle == 0 {
                 return Err(Error::WindowCreate("Unable to open Window".to_owned()));
             }
@@ -464,7 +489,6 @@ impl Window {
         let bytes_per_line = (width as i32) * 4;
 
         draw_buffer.resize(width * height, 0);
-
         let image = (d.lib.XCreateImage)(
             d.display,
             d.visual, /* TODO: this was CopyFromParent in the C code */

src/os/windows/mod.rs

@@ -535,6 +535,12 @@ impl Window {
                 flags &= !winuser::WS_THICKFRAME;
             }
 
+            //TODO: UpdateLayeredWindow, etc.
+            //https://gist.github.com/texus/31676aba4ca774b1298e1e15133b8141
+            if opts.transparency {
+                flags &= winuser::WS_EX_LAYERED;
+            }
+
             let handle = winuser::CreateWindowExW(
                 0,
                 class_name.as_ptr(),