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Handle cell text overflow with ellipsis or clipping #341

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Handle cell text overflow with ellipsis or clipping #341

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181dfb9
Configure text renderer's overflow behavior
nmichaud May 31, 2018
b167d4e
Add configurability of cell text overflow behavior
nmichaud May 31, 2018
b10415f
Use clipping as the default overflow mode
nmichaud Jun 7, 2018
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46 changes: 44 additions & 2 deletions packages/datagrid/src/textrenderer.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -31,6 +31,7 @@ class TextRenderer extends CellRenderer {
this.backgroundColor = options.backgroundColor || '';
this.verticalAlignment = options.verticalAlignment || 'center';
this.horizontalAlignment = options.horizontalAlignment || 'left';
this.overflow = options.overflow || 'clip';
this.format = options.format || TextRenderer.formatGeneric();
}

Expand Down Expand Up @@ -59,6 +60,11 @@ class TextRenderer extends CellRenderer {
*/
readonly horizontalAlignment: CellRenderer.ConfigOption<TextRenderer.HorizontalAlignment>;

/**
* The overflow behavior for the cell text.
*/
readonly overflow: CellRenderer.ConfigOption<TextRenderer.Overflow>;

/**
* The format function for the cell value.
*/
Expand Down Expand Up @@ -186,6 +192,7 @@ class TextRenderer extends CellRenderer {
// Set up the text position variables.
let textX: number;
let textY: number;
let boxWidth: number;

// Compute the Y position for the text.
switch (vAlign) {
Expand All @@ -205,13 +212,16 @@ class TextRenderer extends CellRenderer {
// Compute the X position for the text.
switch (hAlign) {
case 'left':
textX = config.x + 2;
textX = config.x + 8;
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Why the change to the original padding? Should we make that configurable?

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Probably should be configurable. I found a slightly larger padding led to better white space balancing and made the grid much easier to scan and read when using it with real data.

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IIRC I got the original padding values from Excel on Windows.

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Ok, I'll change it back, or add it as an option.

boxWidth = config.width - 14;
break;
case 'center':
textX = config.x + config.width / 2;
boxWidth = config.width;
break;
case 'right':
textX = config.x + config.width - 3;
textX = config.x + config.width - 8;
boxWidth = config.width - 14;
break;
default:
throw 'unreachable';
Expand All @@ -224,6 +234,25 @@ class TextRenderer extends CellRenderer {
gc.clip();
}

let overflow = CellRenderer.resolveOption(this.overflow, config);

if (overflow === 'ellipsis') {
let elide = '\u2026';
let textWidth = gc.measureText(text).width;

// Compute elided text
while ((textWidth > boxWidth) && (text.length > 1)) {
if (text.length > 4 && textWidth >= 2 * boxWidth) {
// If text width is substantially bigger, take half the string
text = text.substr(0, (text.length / 2) + 1) + elide;
} else {
// Otherwise incrementally remove the last character
text = text.substr(0, text.length - 2) + elide;
}
textWidth = gc.measureText(text).width;
}
}

// Set the gc state.
gc.font = font;
gc.fillStyle = color;
Expand Down Expand Up @@ -253,6 +282,12 @@ namespace TextRenderer {
export
type HorizontalAlignment = 'left' | 'center' | 'right';

/**
* A type alias for the supported overflow modes.
*/
export
type Overflow = 'clip' | 'ellipsis';

/**
* An options object for initializing a text renderer.
*/
Expand Down Expand Up @@ -293,6 +328,13 @@ namespace TextRenderer {
*/
horizontalAlignment?: CellRenderer.ConfigOption<HorizontalAlignment>;

/**
* The overflow behavior for text.
*
* The default is `'clip'`.
*/
overflow?: CellRenderer.ConfigOption<Overflow>;

/**
* The format function for the renderer.
*
Expand Down