Noah Petherbridge
b06c52a705
* MainWindow is ideal for apps that just want a UI and don't manage their own SDL windows. * The example app will grow into a series of demos that test the UI toolkit to help fix bugs and grow features.
127 lines
2.4 KiB
Go
127 lines
2.4 KiB
Go
package ui
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import (
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"fmt"
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"time"
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"git.kirsle.net/apps/doodle/lib/render"
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"git.kirsle.net/apps/doodle/lib/render/sdl"
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)
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// Target frames per second for the MainWindow to render at.
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var (
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FPS = 60
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)
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// MainWindow is the parent window of a UI application.
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type MainWindow struct {
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engine render.Engine
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supervisor *Supervisor
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frame *Frame
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w int
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h int
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}
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// NewMainWindow initializes the MainWindow. You should probably only have one
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// of these per application.
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func NewMainWindow(title string) (*MainWindow, error) {
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mw := &MainWindow{
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w: 800,
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h: 600,
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supervisor: NewSupervisor(),
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}
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mw.engine = sdl.New(
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title,
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mw.w,
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mw.h,
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)
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if err := mw.engine.Setup(); err != nil {
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return nil, err
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}
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// Add a default frame to the window.
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mw.frame = NewFrame("MainWindow Body")
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mw.frame.SetBackground(render.RGBA(0, 153, 255, 100))
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mw.Add(mw.frame)
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// Compute initial window size.
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mw.resized()
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return mw, nil
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}
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// Add a child widget to the window.
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func (mw *MainWindow) Add(w Widget) {
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mw.supervisor.Add(w)
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}
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// Pack a child widget into the window's default frame.
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func (mw *MainWindow) Pack(w Widget, pack Pack) {
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mw.Add(w)
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mw.frame.Pack(w, pack)
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}
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// resized handles the window being resized.
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func (mw *MainWindow) resized() {
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mw.frame.Resize(render.Rect{
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W: int32(mw.w),
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H: int32(mw.h),
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})
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}
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// Present the window.
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func (mw *MainWindow) Present() {
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mw.supervisor.Present(mw.engine)
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}
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// MainLoop starts the main event loop and blocks until there's an error.
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func (mw *MainWindow) MainLoop() error {
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for true {
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if err := mw.Loop(); err != nil {
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return err
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}
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}
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return nil
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}
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// Loop does one loop of the UI.
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func (mw *MainWindow) Loop() error {
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mw.engine.Clear(render.White)
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// Record how long this loop took.
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start := time.Now()
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// Poll for events.
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ev, err := mw.engine.Poll()
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if err != nil {
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return fmt.Errorf("event poll error: %s", err)
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}
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if ev.Resized.Now {
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w, h := mw.engine.WindowSize()
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if w != mw.w || h != mw.h {
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mw.w = w
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mw.h = h
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mw.resized()
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}
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}
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mw.frame.Compute(mw.engine)
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// Render the child widgets.
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mw.supervisor.Present(mw.engine)
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mw.engine.Present()
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// Delay to maintain target frames per second.
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var delay uint32
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var targetFPS = 1000 / FPS
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elapsed := time.Now().Sub(start) / time.Millisecond
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if targetFPS-int(elapsed) > 0 {
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delay = uint32(targetFPS - int(elapsed))
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}
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mw.engine.Delay(delay)
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return nil
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}
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