Basic integration with new Piet text API

This introduces a new type, TextLayout, that is intended to be a component used by widgets that wish to display text, and which exposes the functionality of the Piet text API. This commit is a checkpoint; it adds only a small amount of new functionality, and largely tries to keep things working as they do currently.
linebender · Sep 8, 2020 · bb5e6ef · bb5e6ef
1 parent efad9ab
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -24,6 +24,7 @@ You can find its changes [documented below](#060---2020-06-01).
 - `Command::to` and `Command::target` to set and get a commands target. ([#1185] by [@finnerale])
 - `Menu` commands can now choose a custom target. ([#1185] by [@finnerale])
 - `Movement::StartOfDocument`, `Movement::EndOfDocument`. ([#1092] by [@sysint64])
+- `TextLayout` type simplifies drawing text ([#1182] by [@cmyr])
 
 ### Changed
 
@@ -418,6 +419,7 @@ Last release without a changelog :(
 [#1171]: https://github.com/linebender/druid/pull/1171
 [#1172]: https://github.com/linebender/druid/pull/1172
 [#1173]: https://github.com/linebender/druid/pull/1173
+[#1182]: https://github.com/linebender/druid/pull/1185
 [#1185]: https://github.com/linebender/druid/pull/1185
 [#1092]: https://github.com/linebender/druid/pull/1092
 

diff --git a/druid-shell/Cargo.toml b/druid-shell/Cargo.toml
@@ -19,7 +19,7 @@ x11 = ["x11rb", "nix", "cairo-sys-rs"]
 [dependencies]
 # NOTE: When changing the piet or kurbo versions, ensure that
 #       the kurbo version included in piet is compatible with the kurbo version specified here.
-piet-common = "0.2.0-pre2"
+piet-common = "0.2.0-pre3"
 kurbo = "0.6.3"
 
 log = "0.4.11"
@@ -79,5 +79,5 @@ version = "0.3.44"
 features = ["Window", "MouseEvent", "CssStyleDeclaration", "WheelEvent", "KeyEvent", "KeyboardEvent"]
 
 [dev-dependencies]
-piet-common = { version = "0.2.0-pre2", features = ["png"] }
+piet-common = { version = "0.2.0-pre3", features = ["png"] }
 simple_logger = { version = "1.9.0", default-features = false }
diff --git a/druid/examples/custom_widget.rs b/druid/examples/custom_widget.rs
@@ -15,9 +15,12 @@
 //! An example of a custom drawing widget.
 
 use druid::kurbo::BezPath;
-use druid::piet::{FontFamily, ImageFormat, InterpolationMode, Text, TextLayoutBuilder};
+use druid::piet::{FontFamily, ImageFormat, InterpolationMode};
 use druid::widget::prelude::*;
-use druid::{Affine, AppLauncher, Color, LocalizedString, Point, Rect, WindowDesc};
+use druid::{
+    Affine, AppLauncher, Color, FontDescriptor, LocalizedString, Point, Rect, TextLayout,
+    WindowDesc,
+};
 
 struct CustomWidget;
 
@@ -54,7 +57,7 @@ impl Widget<String> for CustomWidget {
     // The paint method gets called last, after an event flow.
     // It goes event -> update -> layout -> paint, and each method can influence the next.
     // Basically, anything that changes the appearance of a widget causes a paint.
-    fn paint(&mut self, ctx: &mut PaintCtx, data: &String, _env: &Env) {
+    fn paint(&mut self, ctx: &mut PaintCtx, data: &String, env: &Env) {
         // Let's draw a picture with Piet!
 
         // Clear the whole widget with the color of your choice
@@ -81,21 +84,18 @@ impl Widget<String> for CustomWidget {
         let fill_color = Color::rgba8(0x00, 0x00, 0x00, 0x7F);
         ctx.fill(rect, &fill_color);
 
-        // Text is easy, if you ignore all these unwraps. Just pick a font and a size.
-        // Here's where we actually use the UI state
-        let layout = ctx
-            .text()
-            .new_text_layout(data.as_str())
-            .font(FontFamily::SYSTEM_UI, 24.0)
-            .text_color(fill_color)
-            .build()
-            .unwrap();
+        // Text is easy; in real use TextLayout should be stored in the widget
+        // and reused.
+        let mut layout = TextLayout::new(data.as_str());
+        layout.set_font(FontDescriptor::new(FontFamily::SERIF).with_size(24.0));
+        layout.set_text_color(fill_color);
+        layout.rebuild_if_needed(&mut ctx.text(), env);
 
         // Let's rotate our text slightly. First we save our current (default) context:
         ctx.with_save(|ctx| {
             // Now we can rotate the context (or set a clip path, for instance):
             ctx.transform(Affine::rotate(0.1));
-            ctx.draw_text(&layout, (80.0, 40.0));
+            layout.draw(ctx, (80.0, 40.0));
         });
         // When we exit with_save, the original context's rotation is restored
 

diff --git a/druid/examples/styled_text.rs b/druid/examples/styled_text.rs
@@ -16,14 +16,13 @@
 
 use druid::widget::{Checkbox, Flex, Label, MainAxisAlignment, Painter, Parse, Stepper, TextBox};
 use druid::{
-    theme, AppLauncher, ArcStr, Color, Data, Key, Lens, LensExt, LensWrap, LocalizedString,
-    PlatformError, RenderContext, Widget, WidgetExt, WindowDesc,
+    theme, AppLauncher, Color, Data, FontDescriptor, FontFamily, Key, Lens, LensExt, LensWrap,
+    LocalizedString, PlatformError, RenderContext, Widget, WidgetExt, WindowDesc,
 };
 use std::fmt::Display;
 
-// This is a custom key we'll use with Env to set and get our text size.
-const MY_CUSTOM_TEXT_SIZE: Key<f64> = Key::new("styled_text.custom_text_size");
-const MY_CUSTOM_FONT: Key<ArcStr> = Key::new("styled_text.custom_font");
+// This is a custom key we'll use with Env to set and get our font.
+const MY_CUSTOM_FONT: Key<FontDescriptor> = Key::new("styled_text.custom_font");
 
 #[derive(Clone, Lens, Data)]
 struct AppData {
@@ -73,7 +72,7 @@ fn ui_builder() -> impl Widget<AppData> {
     });
 
     // This is druid's default text style.
-    // It's set by theme::LABEL_COLOR, theme::TEXT_SIZE_NORMAL, and theme::FONT_NAME
+    // It's set by theme::LABEL_COLOR and theme::UI_FONT
     let label =
         Label::new(|data: &String, _env: &_| format!("Default: {}", data)).lens(AppData::text);
 
@@ -88,19 +87,19 @@ fn ui_builder() -> impl Widget<AppData> {
     // to the default font)
     let styled_label = Label::new(|data: &AppData, _env: &_| format!("{}", data))
         .with_text_color(theme::PRIMARY_LIGHT)
-        .with_text_size(MY_CUSTOM_TEXT_SIZE)
         .with_font(MY_CUSTOM_FONT)
         .background(my_painter)
         .on_click(|_, data, _| {
             data.size *= 1.1;
         })
         .env_scope(|env: &mut druid::Env, data: &AppData| {
-            env.set(MY_CUSTOM_TEXT_SIZE, data.size);
-            if data.mono {
-                env.set(MY_CUSTOM_FONT, "monospace");
+            let new_font = if data.mono {
+                FontDescriptor::new(FontFamily::MONOSPACE)
             } else {
-                env.set(MY_CUSTOM_FONT, env.get(theme::FONT_NAME));
+                FontDescriptor::new(FontFamily::SYSTEM_UI)
             }
+            .with_size(data.size);
+            env.set(MY_CUSTOM_FONT, new_font);
         });
 
     let stepper = Stepper::new()
@@ -118,7 +117,10 @@ fn ui_builder() -> impl Widget<AppData> {
 
     let mono_checkbox = Checkbox::new("Monospace").lens(AppData::mono);
 
-    let input = TextBox::new().fix_width(200.0).lens(AppData::text);
+    let input = TextBox::new()
+        .with_text_size(38.0)
+        .fix_width(200.0)
+        .lens(AppData::text);
 
     Flex::column()
         .main_axis_alignment(MainAxisAlignment::Center)
@@ -131,4 +133,5 @@ fn ui_builder() -> impl Widget<AppData> {
         .with_child(mono_checkbox)
         .with_spacer(8.0)
         .with_child(input.padding(5.0))
+        .debug_widget_id()
 }
diff --git a/druid/src/core.rs b/druid/src/core.rs
@@ -19,12 +19,11 @@ use std::collections::{HashMap, VecDeque};
 use crate::bloom::Bloom;
 use crate::contexts::ContextState;
 use crate::kurbo::{Affine, Insets, Point, Rect, Shape, Size, Vec2};
-use crate::piet::{FontFamily, PietTextLayout, RenderContext, Text, TextLayout, TextLayoutBuilder};
 use crate::util::ExtendDrain;
 use crate::{
     BoxConstraints, Color, Command, Data, Env, Event, EventCtx, InternalEvent, InternalLifeCycle,
-    LayoutCtx, LifeCycle, LifeCycleCtx, PaintCtx, Region, Target, TimerToken, UpdateCtx, Widget,
-    WidgetId,
+    LayoutCtx, LifeCycle, LifeCycleCtx, PaintCtx, Region, RenderContext, Target, TextLayout,
+    TimerToken, UpdateCtx, Widget, WidgetId,
 };
 
 /// Our queue type
@@ -51,7 +50,7 @@ pub struct WidgetPod<T, W> {
     env: Option<Env>,
     inner: W,
     // stashed layout so we don't recompute this when debugging
-    debug_widget_text: Option<PietTextLayout>,
+    debug_widget_text: TextLayout,
 }
 
 /// Generic state for all widgets in the hierarchy.
@@ -145,7 +144,7 @@ impl<T, W: Widget<T>> WidgetPod<T, W> {
             old_data: None,
             env: None,
             inner,
-            debug_widget_text: None,
+            debug_widget_text: TextLayout::new(""),
         }
     }
 
@@ -429,7 +428,7 @@ impl<T: Data, W: Widget<T>> WidgetPod<T, W> {
     }
 
     fn make_widget_id_layout_if_needed(&mut self, id: WidgetId, ctx: &mut PaintCtx, env: &Env) {
-        if self.debug_widget_text.is_none() {
+        if self.debug_widget_text.needs_rebuild() {
             // switch text color based on background, this is meh and that's okay
             let border_color = env.get_debug_color(id.to_raw());
             let (r, g, b, _) = border_color.as_rgba8();
@@ -439,34 +438,29 @@ impl<T: Data, W: Widget<T>> WidgetPod<T, W> {
             } else {
                 Color::BLACK
             };
-
             let id_string = id.to_raw().to_string();
-            self.debug_widget_text = ctx
-                .text()
-                .new_text_layout(id_string)
-                .font(FontFamily::SYSTEM_UI, 10.0)
-                .text_color(text_color)
-                .build()
-                .ok();
+            self.debug_widget_text.set_text(id_string);
+            self.debug_widget_text.set_text_size(10.0);
+            self.debug_widget_text.set_text_color(text_color);
+            self.debug_widget_text
+                .rebuild_if_needed(&mut ctx.text(), env);
         }
     }
 
     fn debug_paint_widget_ids(&self, ctx: &mut PaintCtx, env: &Env) {
         // we clone because we need to move it for paint_with_z_index
         let text = self.debug_widget_text.clone();
-        if let Some(text) = text {
-            let text_size = text.size();
-            let origin = ctx.size().to_vec2() - text_size.to_vec2();
-            let border_color = env.get_debug_color(ctx.widget_id().to_raw());
-            self.debug_paint_layout_bounds(ctx, env);
-
-            ctx.paint_with_z_index(ctx.depth(), move |ctx| {
-                let origin = Point::new(origin.x.max(0.0), origin.y.max(0.0));
-                let text_rect = Rect::from_origin_size(origin, text_size);
-                ctx.fill(text_rect, &border_color);
-                ctx.draw_text(&text, origin);
-            })
-        }
+        let text_size = text.size();
+        let origin = ctx.size().to_vec2() - text_size.to_vec2();
+        let border_color = env.get_debug_color(ctx.widget_id().to_raw());
+        self.debug_paint_layout_bounds(ctx, env);
+
+        ctx.paint_with_z_index(ctx.depth(), move |ctx| {
+            let origin = Point::new(origin.x.max(0.0), origin.y.max(0.0));
+            let text_rect = Rect::from_origin_size(origin, text_size);
+            ctx.fill(text_rect, &border_color);
+            text.draw(ctx, origin);
+        })
     }
 
     fn debug_paint_layout_bounds(&self, ctx: &mut PaintCtx, env: &Env) {
@@ -1008,7 +1002,7 @@ mod tests {
             state: &mut state,
         };
 
-        let env = Env::default();
+        let env = crate::theme::init();
 
         widget.lifecycle(&mut ctx, &LifeCycle::WidgetAdded, &None, &env);
         assert!(ctx.widget_state.children.may_contain(&ID_1));

diff --git a/druid/src/env.rs b/druid/src/env.rs
@@ -87,7 +87,7 @@ struct EnvImpl {
 ///
 /// [`ValueType`]: trait.ValueType.html
 /// [`Env`]: struct.Env.html
-#[derive(Clone)]
+#[derive(Clone, Debug)]
 pub struct Key<T> {
     key: &'static str,
     value_type: PhantomData<*const T>,
@@ -120,7 +120,7 @@ pub enum Value {
 ///
 /// [`Key<T>`]: struct.Key.html
 /// [`Env`]: struct.Env.html
-#[derive(Clone)]
+#[derive(Clone, Debug)]
 pub enum KeyOrValue<T> {
     /// A concrete [`Value`] of type `T`.
     ///

diff --git a/druid/src/lib.rs b/druid/src/lib.rs
@@ -197,7 +197,7 @@ pub use lens::{Lens, LensExt, LensWrap};
 pub use localization::LocalizedString;
 pub use menu::{sys as platform_menus, ContextMenu, MenuDesc, MenuItem};
 pub use mouse::MouseEvent;
-pub use text::FontDescriptor;
+pub use text::{FontDescriptor, TextLayout};
 pub use widget::{Widget, WidgetExt, WidgetId};
 pub use win_handler::DruidHandler;
 pub use window::{Window, WindowId};