Add error checks

ebitenutil/debugprint.go

@@ -64,7 +64,7 @@ func DebugPrint(image *ebiten.Image, str string) error {
 	return defaultDebugPrintState.DebugPrint(image, str)
 }
 
-func (d *debugPrintState) drawText(rt *ebiten.Image, str string, x, y int, c color.Color) {
+func (d *debugPrintState) drawText(rt *ebiten.Image, str string, x, y int, c color.Color) error {
 	ur, ug, ub, ua := c.RGBA()
 	const max = math.MaxUint16
 	r := float64(ur) / max
@@ -81,7 +81,10 @@ func (d *debugPrintState) drawText(rt *ebiten.Image, str string, x, y int, c col
 	}
 	op.GeoM.Translate(float64(x+1), float64(y))
 	op.ColorM.Scale(r, g, b, a)
-	rt.DrawImage(d.textImage, op)
+	if err := rt.DrawImage(d.textImage, op); err != nil {
+		return err
+	}
+	return nil
 }
 
 // DebugPrint prints the given text str on the given image r.
@@ -104,7 +107,11 @@ func (d *debugPrintState) DebugPrint(r *ebiten.Image, str string) error {
 			return err
 		}
 	}
-	d.drawText(r, str, 1, 1, color.NRGBA{0x00, 0x00, 0x00, 0x80})
+	if err := d.drawText(r, str, 1, 1, color.NRGBA{0x00, 0x00, 0x00, 0x80}); err != nil {
-	d.drawText(r, str, 0, 0, color.NRGBA{0xff, 0xff, 0xff, 0xff})
+		return err
+	}
+	if err := d.drawText(r, str, 0, 0, color.NRGBA{0xff, 0xff, 0xff, 0xff}); err != nil {
+		return err
+	}
 	return nil
 }

graphicscontext.go

@@ -47,13 +47,19 @@ func (c *graphicsContext) GLContext() *opengl.Context {
 
 func (c *graphicsContext) SetSize(screenWidth, screenHeight int, screenScale float64) error {
 	if c.screen != nil {
-		c.screen.Dispose()
+		if err := c.screen.Dispose(); err != nil {
+			return err
+		}
 	}
 	if c.offscreen != nil {
-		c.offscreen.Dispose()
+		if err := c.offscreen.Dispose(); err != nil {
+			return err
+		}
 	}
 	if c.offscreen2 != nil {
-		c.offscreen2.Dispose()
+		if err := c.offscreen2.Dispose(); err != nil {
+			return err
+		}
 	}
 	offscreen, err := newVolatileImage(screenWidth, screenHeight, FilterNearest)
 	if err != nil {
@@ -74,7 +80,9 @@ func (c *graphicsContext) SetSize(screenWidth, screenHeight int, screenScale flo
 	if err != nil {
 		return err
 	}
-	c.screen.Clear()
+	if err := c.screen.Clear(); err != nil {
+		return err
+	}
 
 	c.offscreen = offscreen
 	c.offscreen2 = offscreen2

internal/graphics/command.go

@@ -182,7 +182,9 @@ func (c *drawImageCommand) Exec(context *opengl.Context, indexOffsetInBytes int)
 		geoM:             c.geo,
 		colorM:           c.color,
 	}
-	p.begin()
+	if err := p.begin(); err != nil {
+		return err
+	}
 	defer p.end()
 	// TODO: We should call glBindBuffer here?
 	// The buffer is already bound at begin() but it is counterintuitive.

internal/graphics/program.go

@@ -56,7 +56,9 @@ func Reset(context *opengl.Context) error {
 }
 
 func (s *openGLState) reset(context *opengl.Context) error {
-	context.Reset()
+	if err := context.Reset(); err != nil {
+		return err
+	}
 	s.lastProgram = zeroProgram
 	s.lastProjectionMatrix = nil
 	s.lastModelviewMatrix = nil
@@ -132,7 +134,7 @@ type programContext struct {
 	colorM           Matrix
 }
 
-func (p *programContext) begin() {
+func (p *programContext) begin() error {
 	c := p.context
 	if p.state.lastProgram != p.program {
 		c.UseProgram(p.program)
@@ -215,7 +217,10 @@ func (p *programContext) begin() {
 
 	// We don't have to call gl.ActiveTexture here: GL_TEXTURE0 is the default active texture
 	// See also: https://www.opengl.org/sdk/docs/man2/xhtml/glActiveTexture.xml
-	c.BindTexture(p.texture)
+	if err := c.BindTexture(p.texture); err != nil {
+		return err
+	}
+	return nil
 }
 
 func (p *programContext) end() {

run.go

@@ -81,7 +81,9 @@ func Run(f func(*Image) error, width, height int, scale float64, title string) e
 		}
 		close(ch)
 	}()
-	ui.Main()
+	if err := ui.Main(); err != nil {
+		return err
+	}
 	return <-ch
 }