fix: revert breaking change in PNGDecoder

Author: targos

src/PNGEncoder.ts

@@ -140,9 +140,9 @@ function checkInteger(value: number, name: string): number {
 function getColourType(
   data: IImageData
 ): { channels: number; bitDepth: number; colourType: number } {
-  const { channels = 4, bitDepth = 8 } = data;
-  if (channels !== 4 && channels !== 3 && channels !== 2 && channels !== 1) {
-    throw new RangeError(`unsupported number of channels: ${channels}`);
+  let { components = 3, bitDepth = 8 } = data;
+  if (components !== 3 && components !== 1) {
+    throw new RangeError(`unsupported number of components: ${components}`);
   }
   if (bitDepth !== 8 && bitDepth !== 16) {
     throw new RangeError(`unsupported bit depth: ${bitDepth}`);
@@ -156,6 +156,7 @@ function getColourType(
     throw new TypeError(`unsupported alpha: ${alpha}`);
   }
 
+  const channels = components + Number(alpha);
   const returnValue = { channels, bitDepth, colourType: -1 };
   switch (channels) {
     case 4:

src/__tests__/encode.test.ts

@@ -48,7 +48,7 @@ describe('encode', () => {
       width: 2,
       height: 3,
       data: dataArray,
-      channels: 1,
+      components: 1,
       alpha: false
     });
     expect(data).toBeInstanceOf(Uint8Array);
@@ -85,7 +85,7 @@ describe('encode', () => {
       height: 2,
       bitDepth: 16,
       data: dataArray,
-      channels: 3,
+      components: 3,
       alpha: false
     });
     expect(data).toBeInstanceOf(Uint8Array);
@@ -121,7 +121,7 @@ describe('encode', () => {
       width: 2,
       height: 3,
       data: dataArray,
-      channels: 2,
+      components: 1,
       alpha: true
     });
     expect(data).toBeInstanceOf(Uint8Array);
@@ -145,17 +145,17 @@ describe('encode', () => {
         height: 1,
         bitDepth: 8,
         data: new Uint8Array(),
-        channels: 5,
+        components: 5,
         alpha: true
       })
-    ).toThrow('unsupported number of channels: 5');
+    ).toThrow('unsupported number of components: 5');
     expect(() =>
       encode({
         width: 1,
         height: 1,
         bitDepth: 8,
         data: new Uint8Array(),
-        channels: 3,
+        components: 3,
         // @ts-ignore
         alpha: 2
       })
@@ -166,7 +166,7 @@ describe('encode', () => {
         height: 1,
         bitDepth: 8,
         data: new Uint8Array(),
-        channels: 3,
+        components: 3,
         alpha: false
       })
     ).toThrow('width must be a positive integer');
@@ -177,7 +177,7 @@ describe('encode', () => {
         height: undefined,
         bitDepth: 8,
         data: new Uint8Array(),
-        channels: 3,
+        components: 3,
         alpha: false
       })
     ).toThrow('height must be a positive integer');
@@ -187,7 +187,7 @@ describe('encode', () => {
         height: 1,
         bitDepth: 8,
         data: new Uint8Array(10),
-        channels: 3,
+        components: 3,
         alpha: false
       })
     ).toThrow('wrong data size. Found 10, expected 3');
@@ -197,7 +197,7 @@ describe('encode', () => {
         height: 1,
         bitDepth: 1,
         data: new Uint8Array(10),
-        channels: 3,
+        components: 3,
         alpha: false
       })
     ).toThrow('unsupported bit depth: 1');

src/types.ts

@@ -31,7 +31,7 @@ export interface IImageData {
   width: number;
   height: number;
   data: PNGDataArray;
-  channels?: number;
+  components?: number;
   alpha?: boolean | 0 | 1;
   bitDepth?: number;
 }