refacto ts + ajout de dessin simple + ajout pinceau

WIP lib graphique

rootfs overrides/chibrax/graphics.js

@@ -58,9 +58,9 @@ async function readImgFile(filepath) {
 /**
  * @param { number } x
  * @param { number } y
- * @param { import('@jimp/core').Bitmap } bitmap
+ * @param { import('@jimp/core').Bitmap | Pencil } bitmap
  */
-function drawBitmap(x, y, bitmap) {
+function drawBitmap(x, y, bitmap, handleTransparency = true) {
     for(let dy = 0; dy < bitmap.height; dy++) {
         let bitmapLineEnd = bitmap.width * screen.byteDepth * (dy + 1)
         let bitmapLineStart = bitmap.width * screen.byteDepth * dy
@@ -94,7 +94,25 @@ function drawBitmap(x, y, bitmap) {
 
 
         const line = bitmap.data.subarray(bitmapLineStart, bitmapLineEnd)
-        buffer.set(Array.from(line), dx * screen.byteDepth + screen.width * (dy + y) * screen.byteDepth)
+
+        const bufferPlacement =  dx * screen.byteDepth + screen.width * (dy + y) * screen.byteDepth
+
+        if(handleTransparency) {
+            const currentLine = buffer.subarray(bufferPlacement, bufferPlacement + line.length)
+            for(let i=0; i < line.length; i += 4) {
+                const transparency = line.readUInt8(i+3) / 255
+                if(transparency < 1) {
+                    /** @type { Uint8Array } */
+                    const newLine = new Uint8Array(3)
+                    for(let j=0; j < 3; j++) {
+                        newLine[j] = (currentLine.readUInt8(j+i)*1-transparency + line.readUInt8(j+i)*transparency)
+                    }
+                    line.set(newLine, i)
+                }
+            }
+        }
+
+        buffer.set(Array.from(line), bufferPlacement)
     }
 }