%PDF-
%PDF-
Mini Shell
Mini Shell
define(function (require) {
var textWidthCache = {};
var textWidthCacheCounter = 0;
var TEXT_CACHE_MAX = 5000;
var util = require('../core/util');
var BoundingRect = require('../core/BoundingRect');
function getTextWidth(text, textFont) {
var key = text + ':' + textFont;
if (textWidthCache[key]) {
return textWidthCache[key];
}
var textLines = (text + '').split('\n');
var width = 0;
for (var i = 0, l = textLines.length; i < l; i++) {
// measureText 可以被覆盖以兼容不支持 Canvas 的环境
width = Math.max(textContain.measureText(textLines[i], textFont).width, width);
}
if (textWidthCacheCounter > TEXT_CACHE_MAX) {
textWidthCacheCounter = 0;
textWidthCache = {};
}
textWidthCacheCounter++;
textWidthCache[key] = width;
return width;
}
function getTextRect(text, textFont, textAlign, textBaseline) {
var textLineLen = ((text || '') + '').split('\n').length;
var width = getTextWidth(text, textFont);
// FIXME 高度计算比较粗暴
var lineHeight = getTextWidth('国', textFont);
var height = textLineLen * lineHeight;
var rect = new BoundingRect(0, 0, width, height);
// Text has a special line height property
rect.lineHeight = lineHeight;
switch (textBaseline) {
case 'bottom':
case 'alphabetic':
rect.y -= lineHeight;
break;
case 'middle':
rect.y -= lineHeight / 2;
break;
// case 'hanging':
// case 'top':
}
// FIXME Right to left language
switch (textAlign) {
case 'end':
case 'right':
rect.x -= rect.width;
break;
case 'center':
rect.x -= rect.width / 2;
break;
// case 'start':
// case 'left':
}
return rect;
}
function adjustTextPositionOnRect(textPosition, rect, textRect, distance) {
var x = rect.x;
var y = rect.y;
var height = rect.height;
var width = rect.width;
var textHeight = textRect.height;
var halfHeight = height / 2 - textHeight / 2;
var textAlign = 'left';
switch (textPosition) {
case 'left':
x -= distance;
y += halfHeight;
textAlign = 'right';
break;
case 'right':
x += distance + width;
y += halfHeight;
textAlign = 'left';
break;
case 'top':
x += width / 2;
y -= distance + textHeight;
textAlign = 'center';
break;
case 'bottom':
x += width / 2;
y += height + distance;
textAlign = 'center';
break;
case 'inside':
x += width / 2;
y += halfHeight;
textAlign = 'center';
break;
case 'insideLeft':
x += distance;
y += halfHeight;
textAlign = 'left';
break;
case 'insideRight':
x += width - distance;
y += halfHeight;
textAlign = 'right';
break;
case 'insideTop':
x += width / 2;
y += distance;
textAlign = 'center';
break;
case 'insideBottom':
x += width / 2;
y += height - textHeight - distance;
textAlign = 'center';
break;
case 'insideTopLeft':
x += distance;
y += distance;
textAlign = 'left';
break;
case 'insideTopRight':
x += width - distance;
y += distance;
textAlign = 'right';
break;
case 'insideBottomLeft':
x += distance;
y += height - textHeight - distance;
break;
case 'insideBottomRight':
x += width - distance;
y += height - textHeight - distance;
textAlign = 'right';
break;
}
return {
x: x,
y: y,
textAlign: textAlign,
textBaseline: 'top'
};
}
/**
* Show ellipsis if overflow.
*
* @param {string} text
* @param {string} textFont
* @param {string} containerWidth
* @param {Object} [options]
* @param {number} [options.ellipsis='...']
* @param {number} [options.maxIterations=3]
* @param {number} [options.minCharacters=3]
* @return {string}
*/
function textEllipsis(text, textFont, containerWidth, options) {
if (!containerWidth) {
return '';
}
options = util.defaults({
ellipsis: '...',
minCharacters: 3,
maxIterations: 3,
cnCharWidth: getTextWidth('国', textFont),
// FIXME
// 未考虑非等宽字体
ascCharWidth: getTextWidth('a', textFont)
}, options, true);
containerWidth -= getTextWidth(options.ellipsis);
var textLines = (text + '').split('\n');
for (var i = 0, len = textLines.length; i < len; i++) {
textLines[i] = textLineTruncate(
textLines[i], textFont, containerWidth, options
);
}
return textLines.join('\n');
}
function textLineTruncate(text, textFont, containerWidth, options) {
// FIXME
// 粗糙得写的，尚未考虑性能和各种语言、字体的效果。
for (var i = 0;; i++) {
var lineWidth = getTextWidth(text, textFont);
if (lineWidth < containerWidth || i >= options.maxIterations) {
text += options.ellipsis;
break;
}
var subLength = i === 0
? estimateLength(text, containerWidth, options)
: Math.floor(text.length * containerWidth / lineWidth);
if (subLength < options.minCharacters) {
text = '';
break;
}
text = text.substr(0, subLength);
}
return text;
}
function estimateLength(text, containerWidth, options) {
var width = 0;
var i = 0;
for (var len = text.length; i < len && width < containerWidth; i++) {
var charCode = text.charCodeAt(i);
width += (0 <= charCode && charCode <= 127)
? options.ascCharWidth : options.cnCharWidth;
}
return i;
}
var textContain = {
getWidth: getTextWidth,
getBoundingRect: getTextRect,
adjustTextPositionOnRect: adjustTextPositionOnRect,
ellipsis: textEllipsis,
measureText: function (text, textFont) {
var ctx = util.getContext();
ctx.font = textFont;
return ctx.measureText(text);
}
};
return textContain;
});
Zerion Mini Shell 1.0