Merge pull request #32 from mitchellh/auto-pad

Balanced Viewport Margins/Padding

src/renderer/Metal.zig

@@ -390,14 +390,13 @@ pub fn render(
     defer objc_autoreleasePoolPop(pool);
 
     // If we're resizing, then we have to update a bunch of things...
-    if (critical.screen_size) |screen_size| {
+    if (critical.screen_size) |_| {
-        // Update our grid size
+        // Note: we ignore the screen size value because our view should be
-        try self.setScreenSize(screen_size);
+        // automatically updated by being in the window.
-
-        const bounds = self.swapchain.getProperty(macos.graphics.Rect, "bounds");
 
         // Scale the bounds based on the layer content scale so that we
         // properly handle Retina.
+        const bounds = self.swapchain.getProperty(macos.graphics.Rect, "bounds");
         const scaled: macos.graphics.Size = scaled: {
             const scaleFactor = self.swapchain.getProperty(macos.graphics.c.CGFloat, "contentsScale");
             break :scaled .{
@@ -406,25 +405,8 @@ pub fn render(
             };
         };
 
-        // Set the size of the drawable surface to the scaled bounds
+        // Handle our new size
-        self.swapchain.setProperty("drawableSize", scaled);
+        try self.setScreenSize(scaled);
-        //log.warn("bounds={} screen={} scaled={}", .{ bounds, screen_size, scaled });
-
-        // Setup our uniforms
-        const old = self.uniforms;
-        self.uniforms = .{
-            .projection_matrix = math.ortho2d(
-                0,
-                @floatCast(f32, scaled.width),
-                @floatCast(f32, scaled.height),
-                0,
-            ),
-            .cell_size = .{ self.cell_size.width, self.cell_size.height },
-            .underline_position = old.underline_position,
-            .underline_thickness = old.underline_thickness,
-            .strikethrough_position = old.strikethrough_position,
-            .strikethrough_thickness = old.strikethrough_thickness,
-        };
     }
 
     // Build our GPU cells
@@ -572,10 +554,22 @@ pub fn render(
 }
 
 /// Resize the screen.
-fn setScreenSize(self: *Metal, dim: renderer.ScreenSize) !void {
+fn setScreenSize(self: *Metal, bounds: macos.graphics.Size) !void {
+    // Easier to work with our own types
+    const dim: renderer.ScreenSize = .{
+        .width = @floatToInt(u32, bounds.width),
+        .height = @floatToInt(u32, bounds.height),
+    };
+
     // Recalculate the rows/columns.
     const grid_size = renderer.GridSize.init(dim, self.cell_size);
 
+    // Determine if we need to pad the window. For "auto" padding, we take
+    // the leftover amounts on the right/bottom that don't fit a full grid cell
+    // and we split them equal across all boundaries.
+    const padding = renderer.Padding.balanced(dim, grid_size, self.cell_size);
+    const padded_dim = dim.subPadding(padding);
+
     // Update our shaper
     // TODO: don't reallocate if it is close enough (but bigger)
     var shape_buf = try self.alloc.alloc(font.Shaper.Cell, grid_size.columns * 2);
@@ -583,6 +577,25 @@ fn setScreenSize(self: *Metal, dim: renderer.ScreenSize) !void {
     self.alloc.free(self.font_shaper.cell_buf);
     self.font_shaper.cell_buf = shape_buf;
 
+    // Set the size of the drawable surface to the bounds
+    self.swapchain.setProperty("drawableSize", bounds);
+
+    // Setup our uniforms
+    const old = self.uniforms;
+    self.uniforms = .{
+        .projection_matrix = math.ortho2d(
+            -1 * padding.left,
+            @intToFloat(f32, padded_dim.width),
+            @intToFloat(f32, padded_dim.height),
+            -1 * padding.top,
+        ),
+        .cell_size = .{ self.cell_size.width, self.cell_size.height },
+        .underline_position = old.underline_position,
+        .underline_thickness = old.underline_thickness,
+        .strikethrough_position = old.strikethrough_position,
+        .strikethrough_thickness = old.strikethrough_thickness,
+    };
+
     log.debug("screen size screen={} grid={}, cell={}", .{ dim, grid_size, self.cell_size });
 }
 

src/renderer/OpenGL.zig

@@ -547,10 +547,6 @@ pub fn render(
     if (critical.screen_size) |size| {
         // Update our grid size
         try self.setScreenSize(size);
-
-        // Update our viewport for this context to be the entire window.
-        // OpenGL works in pixels, so we have to use the pixel size.
-        try gl.viewport(0, 0, @intCast(i32, size.width), @intCast(i32, size.height));
     }
 
     // Build our GPU cells
@@ -950,24 +946,17 @@ pub fn updateCell(
 /// Set the screen size for rendering. This will update the projection
 /// used for the shader so that the scaling of the grid is correct.
 fn setScreenSize(self: *OpenGL, dim: renderer.ScreenSize) !void {
-    // Update the projection uniform within our shader
-    const bind = try self.program.use();
-    defer bind.unbind();
-    try self.program.setUniform(
-        "projection",
-
-        // 2D orthographic projection with the full w/h
-        math.ortho2d(
-            0,
-            @intToFloat(f32, dim.width),
-            @intToFloat(f32, dim.height),
-            0,
-        ),
-    );
-
     // Recalculate the rows/columns.
     const grid_size = renderer.GridSize.init(dim, self.cell_size);
 
+    // Determine if we need to pad the window. For "auto" padding, we take
+    // the leftover amounts on the right/bottom that don't fit a full grid cell
+    // and we split them equal across all boundaries.
+    const padding = renderer.Padding.balanced(dim, grid_size, self.cell_size);
+    const padded_dim = dim.subPadding(padding);
+
+    log.debug("screen size padded={} screen={} grid={} cell={}", .{ padded_dim, dim, grid_size, self.cell_size });
+
     // Update our LRU. We arbitrarily support a certain number of pages here.
     // We also always support a minimum number of caching in case a user
     // is resizing tiny then growing again we can save some of the renders.
@@ -983,7 +972,31 @@ fn setScreenSize(self: *OpenGL, dim: renderer.ScreenSize) !void {
     self.alloc.free(self.font_shaper.cell_buf);
     self.font_shaper.cell_buf = shape_buf;
 
-    log.debug("screen size screen={} grid={}, cell={}", .{ dim, grid_size, self.cell_size });
+    // Update our viewport for this context to be the entire window.
+    // OpenGL works in pixels, so we have to use the pixel size.
+    try gl.viewport(
+        0,
+        0,
+        @intCast(i32, dim.width),
+        @intCast(i32, dim.height),
+    );
+
+    // Update the projection uniform within our shader
+    {
+        const bind = try self.program.use();
+        defer bind.unbind();
+        try self.program.setUniform(
+            "projection",
+
+            // 2D orthographic projection with the full w/h
+            math.ortho2d(
+                -1 * padding.left,
+                @intToFloat(f32, padded_dim.width),
+                @intToFloat(f32, padded_dim.height),
+                -1 * padding.top,
+            ),
+        );
+    }
 }
 
 /// Updates the font texture atlas if it is dirty.

src/renderer/size.zig

@@ -44,6 +44,14 @@ pub const CellSize = struct {
 pub const ScreenSize = struct {
     width: u32,
     height: u32,
+
+    /// Subtract padding from the screen size.
+    pub fn subPadding(self: ScreenSize, padding: Padding) ScreenSize {
+        return .{
+            .width = self.width - @floatToInt(u32, padding.left + padding.right),
+            .height = self.height - @floatToInt(u32, padding.top + padding.bottom),
+        };
+    }
 };
 
 /// The dimensions of the grid itself, in rows/columns units.
@@ -68,6 +76,44 @@ pub const GridSize = struct {
     }
 };
 
+/// The padding to add to a screen.
+pub const Padding = struct {
+    top: f32,
+    bottom: f32,
+    right: f32,
+    left: f32,
+
+    /// Returns padding that balances the whitespace around the screen
+    /// for the given grid and cell sizes.
+    pub fn balanced(screen: ScreenSize, grid: GridSize, cell: CellSize) Padding {
+        // The size of our full grid
+        const grid_width = @intToFloat(f32, grid.columns) * cell.width;
+        const grid_height = @intToFloat(f32, grid.rows) * cell.height;
+
+        // The empty space to the right of a line and bottom of the last row
+        const space_right = @intToFloat(f32, screen.width) - grid_width;
+        const space_bot = @intToFloat(f32, screen.height) - grid_height;
+
+        // The left/right padding is just an equal split.
+        const padding_right = @floor(space_right / 2);
+        const padding_left = padding_right;
+
+        // The top/bottom padding is interesting. Subjectively, lots of padding
+        // at the top looks bad. So instead of always being equal (like left/right),
+        // we force the top padding to be at most equal to the left, and the bottom
+        // padding is the difference thereafter.
+        const padding_top = @min(padding_left, @floor(space_bot / 2));
+        const padding_bot = space_bot - padding_top;
+
+        return .{
+            .top = padding_top,
+            .bottom = padding_bot,
+            .right = padding_right,
+            .left = padding_left,
+        };
+    }
+};
+
 test "GridSize update exact" {
     const testing = std.testing;