imageunity原始尺寸_前端JS获取Image图像宽高尺寸

var IMAGE_HEAD_SIGS &＃61; {GIF: [0x47, 0x49, 0x46], //&＃39;G&＃39; &＃39;I&＃39; &＃39;F&＃39; asciiPNG: [0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a],JPG: [0xff, 0xd8, 0xff, 0xe0],BMP: [0x42, 0x4d]
}


function ReadPNG(bytes) {if (bytes.slice(0, 8).toString() &＃61;&＃61;&＃61; IMAGE_HEAD_SIGS.PNG.toString()) {let width &＃61; readUint32BE(bytes, 16);let height &＃61; readUint32BE(bytes, 20);return { width, height }}
}


function ReadJPG(bytes) {if (bytes.slice(0, 4).toString() &＃61;&＃61;&＃61; IMAGE_HEAD_SIGS.JPG.toString()) { const M_SOF0 &＃61; 0xC0; /* Start Of Frame N */const M_SOF1 &＃61; 0xC1; /* N indicates which compression process */const M_SOF2 &＃61; 0xC2; /* Only SOF0-SOF2 are now in common use */const M_SOF3 &＃61; 0xC3;const M_SOF5 &＃61; 0xC5; /* NB: codes C4 and CC are NOT SOF markers */const M_SOF6 &＃61; 0xC6;const M_SOF7 &＃61; 0xC7;const M_SOF9 &＃61; 0xC9;const M_SOF10 &＃61; 0xCA;const M_SOF11 &＃61; 0xCB;const M_SOF13 &＃61; 0xCD;const M_SOF14 &＃61; 0xCE;const M_SOF15 &＃61; 0xCF;for (let i &＃61; 0; i }


function ReadGIF(bytes) {if (bytes.slice(0, 3).toString() &＃61;&＃61;&＃61; IMAGE_HEAD_SIGS.GIF.toString()) {let width &＃61; readUint16LE(bytes, 6);let height &＃61; readUint16LE(bytes, 8);return { width, height }}
}


function ReadBMP(bytes) {if (bytes.slice(0, 2).toString() &＃61;&＃61;&＃61; IMAGE_HEAD_SIGS.BMP.toString()) {//虽然格式为4字节&＃xff0c;这里取2字节&＃xff0c;只考虑height为正数。&＃xff08;为负数时图像倒置&＃xff09;let height &＃61; readUint16LE(bytes, 22);let width &＃61; readUint16LE(bytes, 18);return { width, height }}
}


npm i image-dimensionjs