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Added axis label multiline support in canvas #18

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Added axis label multiline support in canvas #18

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3cc017d
Added axis label multiline support in canvas
echalone Jan 31, 2014
e344198
Cleaned up formatting
echalone Aug 11, 2014
dcf9207
Updated format
echalone Aug 11, 2014
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209 changes: 186 additions & 23 deletions jquery.flot.axislabels.js
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Original file line number Diff line number Diff line change
Expand Up @@ -72,53 +72,209 @@ WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
plot, opts);
}

// Adjust the label width in canvas (if the option axisLabelAdjustment for
// this axis was set to true) to the max height/width of the axis
// by inserting line breaks as long as needed and possible
CanvasAxisLabel.prototype.adjustLabel = function(box) {

// we'll need those options and it's possible, that they
// haven't yet been set to their default values if not present
if (!this.opts.axisLabelFontSizePixels)
this.opts.axisLabelFontSizePixels = 14;
if (!this.opts.axisLabelFontFamily)
this.opts.axisLabelFontFamily = 'sans-serif';

var widthBox, labelMaxWidth;
var ctx;
var blMadeAdjustment = true;

// if it's x-axis, take the height of the axis as the max width
// of the label, otherwise (y-axis) take the width of the axis
// as the max width of the label
if (this.position == 'left' || this.position == 'right') {
widthBox = box.height;
} else {
widthBox = box.width;
}

// we need to calculate the label width, for that we'll need the canvas
// and set the used font size and family
ctx = this.plot.getCanvas().getContext('2d');
ctx.font = this.opts.axisLabelFontSizePixels + 'px ' + this.opts.axisLabelFontFamily;

// Now get the label width. If there is already more than one line: iterate through
// them and find the line with the widest width.
labelMaxWidth = this.getMaxWidthLabel(ctx);

// now lets do adjustments to the label (inserting line breaks) as long as
// the label width is wider than the height/width of the axis and as long
// as we were able to do adjustments (or if we're just beginning the loop).
while (labelMaxWidth.width > widthBox && blMadeAdjustment) {

// is there a space somewhere in the most broadest line
var idx = labelMaxWidth.lines[labelMaxWidth.index].lastIndexOf(' ');

// If so, insert a line break into this most broadest line and
// join the lines back together so we have our new axis label.
// If we can't break the broadest line it doesn't make sense to
// break any other line, so we would have to leave the loop
// by declaring we haven't done any adjustments.
if (idx > 0) {
// now we insert the line break to the last space(s) of the broadest line
labelMaxWidth.lines[labelMaxWidth.index] = labelMaxWidth.lines[labelMaxWidth.index].replace(/ *([^ ]*)$/, '\n$1');

// and now we join the lines back together with line breaks (since that's how
// we've splittet them into lines) and we have our new axis label
this.opts.axisLabel = labelMaxWidth.lines.join('\n');

// Now lets start all this over again and check if we have our perfect label
// now by getting once more the label width. Since there is now for sure already
// more than one line: iterate through them and find the line with the widest width.
labelMaxWidth = this.getMaxWidthLabel(ctx);
}
else
blMadeAdjustment = false;
}
}

// Lets get the width of the broadest line,
// we'll also need all the lines
// and the index of the broadest line.
// We need this for adjusting the axis label.
CanvasAxisLabel.prototype.getMaxWidthLabel = function(ctx) {
var arrAxisLabel = this.opts.axisLabel.split('\n');
var countLines = arrAxisLabel.length;
var widthLine, widthLabelMax = null, idx = 0;

for (var i = 0; i < countLines; i++) {
widthLine = ctx.measureText(arrAxisLabel[i]).width;
if (widthLabelMax === null || widthLine > widthLabelMax) {
widthLabelMax = widthLine;
idx = i;
}
}

return { width: widthLabelMax, index: idx, lines: arrAxisLabel };
}

CanvasAxisLabel.prototype.calculateSize = function() {
// padding between lines if we have more than one
if (!this.opts.axisLabelLinePadding)
this.opts.axisLabelLinePadding = 5;
if (!this.opts.axisLabelFontSizePixels)
this.opts.axisLabelFontSizePixels = 14;
if (!this.opts.axisLabelFontFamily)
this.opts.axisLabelFontFamily = 'sans-serif';

// How many lines are there in our label? Important if it's a multiline label.
var countLines = this.opts.axisLabel.split('\n').length;
var textWidth = this.opts.axisLabelFontSizePixels + this.padding;
var textHeight = this.opts.axisLabelFontSizePixels + this.padding;

// now calculate the height of line times the number of line adding the padding between lines and the padding to the axis
if (this.position == 'left' || this.position == 'right') {
this.width = this.opts.axisLabelFontSizePixels + this.padding;
this.width = this.opts.axisLabelFontSizePixels * countLines * 0.72 + this.opts.axisLabelLinePadding * (countLines - 1) + this.padding;
this.height = 0;
} else {
this.width = 0;
this.height = this.opts.axisLabelFontSizePixels + this.padding;
this.height = this.opts.axisLabelFontSizePixels * countLines * 0.72 + this.opts.axisLabelLinePadding * (countLines - 1) + this.padding;
}
};

CanvasAxisLabel.prototype.draw = function(box) {
// split our label in multiple lines if there are any line breaks inserted
var arrAxisLabel = this.opts.axisLabel.split('\n');

if (!this.opts.axisLabelColour)
this.opts.axisLabelColour = 'black';

// now set the default value of label alignment if none was given,
// or convert the value 'middle' to value 'center'. This will only
// affect multiline labels.
if (!this.opts.axisLabelAlignment || this.opts.axisLabelAlignment === 'middle')
this.opts.axisLabelAlignment = 'center';

// what is our line count?
var countLines = arrAxisLabel.length;
// array of canvases
var arrCtx = new Array(countLines);
// height of one line
var height = this.opts.axisLabelFontSizePixels;
// get the broadest line width of our multiline label,
// we might need this for alignment.
var ctx = this.plot.getCanvas().getContext('2d');
ctx.font = this.opts.axisLabelFontSizePixels + 'px ' + this.opts.axisLabelFontFamily;
ctx.save();
ctx.font = this.opts.axisLabelFontSizePixels + 'px ' +
this.opts.axisLabelFontFamily;
ctx.fillStyle = this.opts.axisLabelColour;
var width = ctx.measureText(this.opts.axisLabel).width;
var height = this.opts.axisLabelFontSizePixels;
var x, y, angle = 0;
if (this.position == 'top') {
x = box.left + box.width/2 - width/2;
y = box.top + height*0.72;
} else if (this.position == 'bottom') {
x = box.left + box.width/2 - width/2;
y = box.top + box.height - height*0.72;
} else if (this.position == 'left') {
x = box.left + height*0.72;
y = box.height/2 + box.top + width/2;
var labelMaxWidth = this.getMaxWidthLabel(ctx);
var angle = 0;

// angle if this is a y-axis
if (this.position == 'left') {
angle = -Math.PI/2;
} else if (this.position == 'right') {
x = box.left + box.width - height*0.72;
y = box.height/2 + box.top - width/2;
angle = Math.PI/2;
}
ctx.translate(x, y);
ctx.rotate(angle);
ctx.fillText(this.opts.axisLabel, 0, 0);
ctx.restore();

// now lets draw each label line on the chart
for (var i = 0; i < countLines; i++) {
// prepare the canvas for this label
arrCtx[i] = this.plot.getCanvas().getContext('2d');
arrCtx[i].save();
arrCtx[i].font = this.opts.axisLabelFontSizePixels + 'px ' + this.opts.axisLabelFontFamily;
arrCtx[i].fillStyle = this.opts.axisLabelColour;

// measure width of this line
var width = arrCtx[i].measureText(arrAxisLabel[i]).width;
var x, y;

// calculate position of this line
if (this.position == 'top') {
// align the text correct in multiline labels
if (this.opts.axisLabelAlignment === 'left')
x = box.left + box.width/2 - labelMaxWidth.width/2;
else if (this.opts.axisLabelAlignment === 'right')
x = box.left + box.width/2 + labelMaxWidth.width/2 - width;
else
x = box.left + box.width/2 - width/2;
// calculate the position of one label line
y = box.top + height * (i + 1) * 0.72 + this.opts.axisLabelLinePadding * i;
} else if (this.position == 'bottom') {
// align the text correct in multiline labels
if (this.opts.axisLabelAlignment === 'left')
x = box.left + box.width/2 - labelMaxWidth.width/2;
else if (this.opts.axisLabelAlignment === 'right')
x = box.left + box.width/2 + labelMaxWidth.width/2 - width;
else
x = box.left + box.width/2 - width/2;
// calculate the position of one label line
y = box.top + box.height - height * (countLines - i) * 0.72 - this.opts.axisLabelLinePadding * (countLines - i - 1);
} else if (this.position == 'left') {
// calculate the position of one label line
x = box.left + height * (i + 1) * 0.72 + this.opts.axisLabelLinePadding * i;
// align the text correct in multiline labels
if (this.opts.axisLabelAlignment === 'left')
y = box.top + box.height/2 + labelMaxWidth.width/2;
else if (this.opts.axisLabelAlignment === 'right')
y = box.top + box.height/2 - labelMaxWidth.width/2 + width;
else
y = box.top + box.height/2 + width/2;
} else if (this.position == 'right') {
// calculate the position of one label line
x = box.left + box.width - height * (i + 1) * 0.72 - this.opts.axisLabelLinePadding * i;
// align the text correct in multiline labels
if (this.opts.axisLabelAlignment === 'left')
y = box.top + box.height/2 - labelMaxWidth.width/2;
else if (this.opts.axisLabelAlignment === 'right')
y = box.top + box.height/2 + labelMaxWidth.width/2 - width;
else
y = box.top + box.height/2 - width/2;
}
// now draw the text of this line
arrCtx[i].translate(x, y);
arrCtx[i].rotate(angle);
arrCtx[i].fillText(arrAxisLabel[i], 0, 0);
arrCtx[i].restore();
}
};


Expand Down Expand Up @@ -403,6 +559,13 @@ WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
axis.position, padding,
plot, opts);

// if the label should be adjusted (enters line breaks if needed)
// then do this now, provided the adjustLabel function exists
// for this kind of axis (currently only in canvas).
if (axisLabels[axisName].opts.axisLabelAdjustment &&
typeof axisLabels[axisName].adjustLabel === 'function')
axisLabels[axisName].adjustLabel(axis.box);

// flot interprets axis.labelHeight and .labelWidth as
// the height and width of the tick labels. We increase
// these values to make room for the axis label and
Expand Down