abletk/abletk-direct2d/src/lib.rs

use std::mem;
use raw_window_handle::Win32Handle;
use windows::{
    core::Interface, Foundation::Numerics::*, Win32::Foundation::*,
    Win32::Graphics::Direct2D::Common::*, Win32::Graphics::Direct2D::*,
    Win32::Graphics::DirectWrite::*, Win32::UI::WindowsAndMessaging::*,
};

/// The default brush color is black.
const DEFAULT_BRUSH_COLOR: D2D1_COLOR_F = D2D1_COLOR_F {
    r: 0.0,
    g: 0.0,
    b: 0.0,
    a: 1.0,
};

const DEFAULT_BRUSH_PROPERTIES: D2D1_BRUSH_PROPERTIES = D2D1_BRUSH_PROPERTIES {
    opacity: 1.0,
    // Matrix3x2::identity() is not a const fn but it could be
    //
    // I (TheOddGarlic) sent windows-rs a PR and it got merged but now we wait
    // for it to be included in the next release
    transform: Matrix3x2 {
        M11: 1.0, M12: 0.0, M21: 0.0, M22: 1.0, M31: 0.0, M32: 0.0
    }
};

pub struct Renderer {
    handle: Win32Handle,
    factory: ID2D1Factory1,
    dw_factory: IDWriteFactory,
    target: Option<ID2D1HwndRenderTarget>,
    brush: Option<ID2D1SolidColorBrush>,
    stroke_style: ID2D1StrokeStyle,
    system_fonts: IDWriteFontCollection,
    text_format: IDWriteTextFormat
}

impl Renderer {
    pub fn new(handle: Win32Handle) -> Self {
        let factory = create_factory();
        let dw_factory = create_dw_factory();
        let system_fonts = create_system_font_collection(&dw_factory);
        let text_format = create_text_format(&dw_factory, &system_fonts);
        let stroke_style = unsafe {
            factory.CreateStrokeStyle(&Default::default(), &[])
                .unwrap()
        };

        Self {
            handle,
            factory,
            dw_factory,
            target: None,
            brush: None,
            stroke_style,
            system_fonts,
            text_format,
        }
    }
    
    pub fn begin_draw(&mut self) {
        self.setup_target();

        unsafe { self.target.as_ref().unwrap().BeginDraw() }
    }

    pub fn clear<C: Into<D2D1_COLOR_F>>(&self, color: C) {
        unsafe { self.target.as_ref().unwrap().Clear(&color.into()) }
    }

    pub fn draw_text(&self, text: &str) {
        unsafe {
            self.target.as_ref().unwrap().DrawText(
                // fixme: make this not hacky
                &text.as_bytes().iter().map(|b| *b as u16).collect::<Vec<_>>(),
                &self.text_format,
                // fixme: unhardcode this (needs layout stuff probably)
                &D2D_RECT_F {
                    left: 0.0,
                    top: 0.0,
                    right: 100.0,
                    bottom: 100.0,
                },
                self.brush.as_ref().unwrap(),
                D2D1_DRAW_TEXT_OPTIONS_NONE,
                DWRITE_MEASURING_MODE_NATURAL,
            );
        }
    }

    pub fn end_draw(&self) {
        unsafe {
            self.target.as_ref().unwrap()
                .EndDraw(std::ptr::null_mut(), std::ptr::null_mut()).unwrap()
        }
    }

    pub fn fill_rect<R: Into<D2D_RECT_F>>(&self, rect: R) {
        unsafe {
            self.target.as_ref().unwrap()
                .FillRectangle(
                    &rect.into(),
                    self.brush.as_ref().unwrap())
        }
    }

    pub fn resized(&mut self, width: u32, height: u32) {
        unsafe {
            if let Some(target) = self.target.as_ref() {
                target.Resize(&D2D_SIZE_U {
                    width,
                    height
                }).unwrap()
            }
        }
    }

    pub fn size(&self) -> (f32, f32) {
        let size = unsafe {
            self.target.as_ref().unwrap().GetSize()
        };
        (size.width, size.height)
    }

    fn setup_target(&mut self) {
        if self.target.is_none() {
            let mut rect = RECT::default();
            unsafe {
                GetClientRect(
                    mem::transmute::<_, HWND>(self.handle.hwnd),
                    &mut rect
                );
            }

            let d2d_rect = D2D_SIZE_U {
                width: (rect.right - rect.left) as u32,
                height: (rect.bottom - rect.top) as u32,
            };

            let render_properties = D2D1_RENDER_TARGET_PROPERTIES::default();
            let hwnd_render_properties = D2D1_HWND_RENDER_TARGET_PROPERTIES {
                hwnd: unsafe { mem::transmute(self.handle.hwnd) },
                pixelSize: d2d_rect,
                presentOptions: D2D1_PRESENT_OPTIONS_NONE,
            };

            let target = unsafe {
                self.factory
                    .CreateHwndRenderTarget(
                        &render_properties,
                        &hwnd_render_properties)
                    .unwrap()
            };

            let brush = unsafe {
                target.CreateSolidColorBrush(&DEFAULT_BRUSH_COLOR, &DEFAULT_BRUSH_PROPERTIES)
                    .unwrap()
            };

            self.target = Some(target);
            self.brush = Some(brush);
        }
    }
}

fn create_factory() -> ID2D1Factory1 {
    let mut options = D2D1_FACTORY_OPTIONS::default();

    if cfg!(debug_assertions) {
        options.debugLevel = D2D1_DEBUG_LEVEL_INFORMATION;
    }

    let mut result = None;

    unsafe {
        D2D1CreateFactory(
            D2D1_FACTORY_TYPE_SINGLE_THREADED,
            &ID2D1Factory1::IID,
            &options,
            mem::transmute(&mut result)
        ).map(|()| result.unwrap())
    }.unwrap()
}

fn create_dw_factory() -> IDWriteFactory {
    unsafe {
        mem::transmute(DWriteCreateFactory(
            DWRITE_FACTORY_TYPE_SHARED,
            &IDWriteFactory::IID
        ).unwrap())
    }
}

fn create_system_font_collection(factory: &IDWriteFactory) -> IDWriteFontCollection {
    unsafe {
        let mut result = None;
        factory.GetSystemFontCollection(&mut result, false)
            .map(|_| result.unwrap())
            .unwrap()
    }
}

fn create_text_format(factory: &IDWriteFactory, fonts: &IDWriteFontCollection)
    -> IDWriteTextFormat
{
    unsafe {
        factory.CreateTextFormat(
            "Arial",
            fonts,
            DWRITE_FONT_WEIGHT_NORMAL,
            DWRITE_FONT_STYLE_NORMAL,
            DWRITE_FONT_STRETCH_NORMAL,
            10.0 * 96.0 / 72.0,
            "en-US",
        ).unwrap()
    }
}