skia2/modules/canvaskit/font.js

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CanvasKit._extraInitializations = CanvasKit._extraInitializations || [];
CanvasKit._extraInitializations.push(function() {
// str can be either a text string or a ShapedText object
CanvasKit.SkCanvas.prototype.drawText = function(str, x, y, paint, font) {
if (typeof str === 'string') {
// lengthBytesUTF8 and stringToUTF8Array are defined in the emscripten
// JS. See https://kripken.github.io/emscripten-site/docs/api_reference/preamble.js.html#stringToUTF8
var strLen = lengthBytesUTF8(str);
// Add 1 for null terminator, which we need when copying/converting, but can ignore
// when we call into Skia.
var strPtr = CanvasKit._malloc(strLen + 1);
stringToUTF8(str, strPtr, strLen + 1);
this._drawSimpleText(strPtr, strLen, x, y, font, paint);
} else {
this._drawShapedText(str, x, y, paint);
}
}
// Returns an array of the widths of the glyphs in this string.
CanvasKit.SkFont.prototype.getWidths = function(str) {
// add 1 for null terminator
var codePoints = str.length + 1;
// lengthBytesUTF8 and stringToUTF8Array are defined in the emscripten
// JS. See https://kripken.github.io/emscripten-site/docs/api_reference/preamble.js.html#stringToUTF8
// Add 1 for null terminator
var strBytes = lengthBytesUTF8(str) + 1;
var strPtr = CanvasKit._malloc(strBytes);
stringToUTF8(str, strPtr, strBytes);
var bytesPerFloat = 4;
// allocate widths == numCodePoints
var widthPtr = CanvasKit._malloc(codePoints * bytesPerFloat);
if (!this._getWidths(strPtr, strBytes, codePoints, widthPtr)) {
SkDebug('Could not compute widths');
CanvasKit._free(strPtr);
CanvasKit._free(widthPtr);
return null;
}
// reminder, this shouldn't copy the data, just is a nice way to
// wrap 4 bytes together into a float.
var widths = new Float32Array(CanvasKit.HEAPU8.buffer, widthPtr, codePoints);
// This copies the data so we can free the CanvasKit memory
var retVal = Array.from(widths);
CanvasKit._free(strPtr);
CanvasKit._free(widthPtr);
return retVal;
}
// arguments should all be arrayBuffers or be an array of arrayBuffers.
CanvasKit.SkFontMgr.FromData = function() {
if (!arguments.length) {
SkDebug('Could not make SkFontMgr from no font sources');
return null;
}
var fonts = arguments;
if (fonts.length === 1 && Array.isArray(fonts[0])) {
fonts = arguments[0];
}
if (!fonts.length) {
SkDebug('Could not make SkFontMgr from no font sources');
return null;
}
var dPtrs = [];
var sizes = [];
for (var i = 0; i < fonts.length; i++) {
var data = new Uint8Array(fonts[i]);
var dptr = copy1dArray(data, CanvasKit.HEAPU8);
dPtrs.push(dptr);
sizes.push(data.byteLength);
}
// Pointers are 32 bit unsigned ints
var datasPtr = copy1dArray(dPtrs, CanvasKit.HEAPU32);
var sizesPtr = copy1dArray(sizes, CanvasKit.HEAPU32);
var fm = CanvasKit.SkFontMgr._fromData(datasPtr, sizesPtr, fonts.length);
// The SkFontMgr has taken ownership of the bytes we allocated in the for loop.
CanvasKit._free(datasPtr);
CanvasKit._free(sizesPtr);
return fm;
}
// fontData should be an arrayBuffer
CanvasKit.SkFontMgr.prototype.MakeTypefaceFromData = function(fontData) {
var data = new Uint8Array(fontData);
var fptr = copy1dArray(data, CanvasKit.HEAPU8);
var font = this._makeTypefaceFromData(fptr, data.byteLength);
if (!font) {
SkDebug('Could not decode font data');
// We do not need to free the data since the C++ will do that for us
// when the font is deleted (or fails to decode);
return null;
}
return font;
}
CanvasKit.SkTextBlob.MakeOnPath = function(str, path, font, initialOffset) {
if (!str || !str.length) {
SkDebug('ignoring 0 length string');
return;
}
if (!path || !path.countPoints()) {
SkDebug('ignoring empty path');
return;
}
if (path.countPoints() === 1) {
SkDebug('path has 1 point, returning normal textblob');
return this.MakeFromText(str, font);
}
if (!initialOffset) {
initialOffset = 0;
}
var widths = font.getWidths(str);
var rsx = new CanvasKit.RSXFormBuilder();
var meas = new CanvasKit.SkPathMeasure(path, false, 1);
var dist = initialOffset;
for (var i = 0; i < str.length; i++) {
var width = widths[i];
dist += width/2;
if (dist > meas.getLength()) {
// jump to next contour
if (!meas.nextContour()) {
// We have come to the end of the path - terminate the string
// right here.
str = str.substring(0, i);
break;
}
dist = width/2;
}
// Gives us the (x, y) coordinates as well as the cos/sin of the tangent
// line at that position.
var xycs = meas.getPosTan(dist);
var cx = xycs[0];
var cy = xycs[1];
var cosT = xycs[2];
var sinT = xycs[3];
var adjustedX = cx - (width/2 * cosT);
var adjustedY = cy - (width/2 * sinT);
rsx.push(cosT, sinT, adjustedX, adjustedY);
dist += width/2;
}
var retVal = this.MakeFromRSXform(str, rsx, font);
rsx.delete();
meas.delete();
return retVal;
}
CanvasKit.SkTextBlob.MakeFromRSXform = function(str, rsxBuilder, font) {
// lengthBytesUTF8 and stringToUTF8Array are defined in the emscripten
// JS. See https://kripken.github.io/emscripten-site/docs/api_reference/preamble.js.html#stringToUTF8
// Add 1 for null terminator
var strLen = lengthBytesUTF8(str) + 1;
var strPtr = CanvasKit._malloc(strLen);
// Add 1 for the null terminator.
stringToUTF8(str, strPtr, strLen);
var rptr = rsxBuilder.build();
var blob = CanvasKit.SkTextBlob._MakeFromRSXform(strPtr, strLen - 1, rptr, font);
if (!blob) {
SkDebug('Could not make textblob from string "' + str + '"');
return null;
}
var origDelete = blob.delete.bind(blob);
blob.delete = function() {
CanvasKit._free(strPtr);
origDelete();
}
return blob;
}
CanvasKit.SkTextBlob.MakeFromText = function(str, font) {
// lengthBytesUTF8 and stringToUTF8Array are defined in the emscripten
// JS. See https://kripken.github.io/emscripten-site/docs/api_reference/preamble.js.html#stringToUTF8
// Add 1 for null terminator
var strLen = lengthBytesUTF8(str) + 1;
var strPtr = CanvasKit._malloc(strLen);
// Add 1 for the null terminator.
stringToUTF8(str, strPtr, strLen);
var blob = CanvasKit.SkTextBlob._MakeFromText(strPtr, strLen - 1, font);
if (!blob) {
SkDebug('Could not make textblob from string "' + str + '"');
return null;
}
var origDelete = blob.delete.bind(blob);
blob.delete = function() {
CanvasKit._free(strPtr);
origDelete();
}
return blob;
}
});