Add PixMap struct

PixMap is a generic data structure for manipulating any kind of pixel data - screen, sprite-sheet etc.

PixMap uses a single byte (8 bits) for storing single color/pixel. This means that max 256 colors can be used.

PixMap can also be used for maps which not necessary contain pixel colors, such as world map (as long as only 256 different tiles are used).

This commit replaces pi.Screen and pi.SpriteSheet with pi.PixMap.

PixMap provides also new methods:

* Copy - copy PixMap fragment to another PixMap at specific location
* Merge - customizable variant of Copy. User can provide his own merge function which will be used instead of directly copying pixels.
* Foreach - run code line by line on selected PixMap fragment
* Pointer - low-level method for high-performance processing

Author: elgopher

devtools/internal/inspector/draw.go

@@ -37,7 +37,7 @@ func Draw() {
 func cursorOutOfWindow() bool {
 	x, y := pi.MousePos()
 	screen := pi.Scr()
-	return x < 0 || x >= screen.W || y < 0 || y >= screen.H
+	return x < 0 || x >= screen.Width() || y < 0 || y >= screen.Height()
 }
 
 func handleScreenshot() {

devtools/internal/inspector/inspector.go

@@ -14,7 +14,7 @@ func moveBarIfNeeded() {
 	switch {
 	case isBarOnTop && mouseY <= 12:
 		isBarOnTop = false
-	case !isBarOnTop && mouseY >= pi.Scr().H-12:
+	case !isBarOnTop && mouseY >= pi.Scr().Height()-12:
 		isBarOnTop = true
 	}
 }

devtools/internal/inspector/measure.go

@@ -29,10 +29,10 @@ func (m *Measure) drawBar() {
 	mouseX, mouseY := pi.MousePos()
 	var barY int
 	if !isBarOnTop {
-		barY = screen.H - 7
+		barY = screen.Height() - 7
 	}
 
-	pi.RectFill(0, barY, screen.W, barY+6, BgColor)
+	pi.RectFill(0, barY, screen.Width(), barY+6, BgColor)
 
 	textX := 1
 	textY := barY + 1

devtools/internal/inspector/toolbar.go

@@ -28,8 +28,8 @@ func (t *Toolbar) toggle() {
 		t.pos.X = 0
 	}
 	scr := pi.Scr()
-	if t.pos.X+toolbarWidth > scr.W {
-		t.pos.X = scr.W - toolbarWidth - 1
+	if t.pos.X+toolbarWidth > scr.Width() {
+		t.pos.X = scr.Width() - toolbarWidth - 1
 	}
 	t.pos.Y -= toolbarHeight + 2
 	if t.pos.Y < 0 {

devtools/internal/snapshot/snapshot.go

@@ -23,14 +23,15 @@ func Take() {
 	}
 
 	screen := pi.Scr()
+	pix := screen.Pix()
 	if snapshot == nil {
-		snapshot = make([]byte, len(screen.Pix))
+		snapshot = make([]byte, len(pix))
 	}
-	copy(snapshot, screen.Pix)
+	copy(snapshot, pix)
 }
 
 func Draw() {
-	copy(pi.Scr().Pix, snapshot)
+	copy(pi.Scr().Pix(), snapshot)
 }
 
 func Undo() {

ebitengine/ebitengine.go

@@ -30,8 +30,8 @@ func Run() error {
 	ebiten.SetScreenClearedEveryFrame(false)
 	ebiten.SetRunnableOnUnfocused(true)
 	ebiten.SetWindowResizingMode(ebiten.WindowResizingModeEnabled)
-	ebiten.SetWindowSize(screen.W*scale(), screen.H*scale())
-	ebiten.SetWindowSizeLimits(screen.W, screen.H, -1, -1)
+	ebiten.SetWindowSize(screen.Width()*scale(), screen.Height()*scale())
+	ebiten.SetWindowSizeLimits(screen.Width(), screen.Height(), -1, -1)
 	ebiten.SetCursorMode(ebiten.CursorModeHidden)
 	ebiten.SetWindowTitle("Pi Game")
 

ebitengine/game.go

@@ -76,7 +76,7 @@ func (e *game) Draw(screen *ebiten.Image) {
 }
 
 func (e *game) writeScreenPixels(screen *ebiten.Image) {
-	pix := pi.Scr().Pix
+	pix := pi.Scr().Pix()
 	if e.screenDataRGBA == nil || len(e.screenDataRGBA)/4 != len(pix) {
 		e.screenDataRGBA = make([]byte, len(pix)*4)
 	}
@@ -96,5 +96,5 @@ func (e *game) writeScreenPixels(screen *ebiten.Image) {
 
 func (e *game) Layout(outsideWidth, outsideHeight int) (screenWidth, screenHeight int) {
 	scr := pi.Scr()
-	return scr.W, scr.H
+	return scr.Width(), scr.Height()
 }

examples/memory/main.go

@@ -11,7 +11,7 @@ import (
 
 func main() {
 	pi.Draw = func() {
-		pixels := pi.Scr().Pix
+		pixels := pi.Scr().Pix()
 		for i := 0; i < len(pixels); i++ {
 			randomColor := byte(rand.Intn(16))
 			pixels[i] = randomColor // put a random color to each pixel

examples/pixmap/main.go

@@ -0,0 +1,39 @@
+// Example showing how to use PixMap struct, which is used to store screen
+// and sprite-sheet pixels.
+package main
+
+import (
+	"embed"
+
+	"github.com/elgopher/pi"
+	"github.com/elgopher/pi/ebitengine"
+)
+
+//go:embed sprite-sheet.png
+var resources embed.FS
+
+func main() {
+	pi.Load(resources)
+
+	// copy from sprite-sheet to sprite-sheet:
+	pi.SprSheet().Copy(10, 0, 100, 100, pi.SprSheet(), 0, 0)
+
+	// draw a filled rectangle directly to sprite-sheet:
+	pi.SprSheet().RectFill(60, 30, 70, 40, 7)
+
+	// merge from sprite-sheet to screen using custom merge function, which merges two lines
+	pi.SprSheet().Merge(-1, -1, 103, 70, pi.Scr(), -1, -1, func(dst, src []byte) {
+		for x := 0; x < len(dst); x++ {
+			dst[x] += pi.DrawPalette[src[x]] + 1
+		}
+	})
+
+	// update each line in a loop:
+	pi.Scr().Foreach(10, 10, 16, 16, func(x, y int, line []byte) {
+		for i := 0; i < len(line); i++ {
+			line[i] = byte(i)
+		}
+	})
+
+	ebitengine.MustRun()
+}