TextEditUtils.java

package com.project.website.canvas.client.canvastools.textedit;

import com.google.gwt.dom.client.Style;
import com.google.gwt.dom.client.Style.Display;
import com.google.gwt.dom.client.Style.Unit;
import com.google.gwt.user.client.ui.HTMLPanel;
import com.google.gwt.user.client.ui.HasText;
import com.google.gwt.user.client.ui.RootPanel;
import com.google.gwt.user.client.ui.Widget;
import com.project.shared.data.Point2D;

public class TextEditUtils {

    static final HTMLPanel testWidget = new HTMLPanel("");
    static boolean testWidgetInit = false;

    static void init() {
        Style targetStyle = testWidget.getElement().getStyle();
        targetStyle.setProperty("width", "auto");
        targetStyle.setProperty("height", "auto");
        targetStyle.setTop(-9999, Unit.PX);
        targetStyle.setLeft(-9999, Unit.PX);
        RootPanel.getBodyElement().appendChild(testWidget.getElement());
        testWidgetInit = true;
    }

    static {
        init();
    }

    protected static Point2D autoSizeWidget(Widget widget, String html, boolean usePreWhiteSpace) {
        if (false == testWidgetInit) {
            init();
        }
        Style targetStyle = testWidget.getElement().getStyle();
        targetStyle.setDisplay(Display.INLINE_BLOCK);

        // This code based on:
        // http://stackoverflow.com/questions/1288297/jquery-auto-size-text-input-not-textarea/1288475#1288475
        int comfortZone = 40;
        int minWidth = 0;
        Style widgetStyle = widget.getElement().getStyle();
        copyTextSizingProps(targetStyle, widgetStyle);
        //targetStyle.setFontSize(16.0, Unit.PX);
        if (usePreWhiteSpace) {
            targetStyle.setProperty("whiteSpace", "pre");
        }

//        // append a char after every newline. fixes some PRE formatting bugs
//        // (esp. last empty line)
//        html.replace("\n", "\nM");
//        // Also prepend a character
//        // (if the text begins with whitespace the browser may strip it in the
//        // test widget)
//        html = html + "<br>";
        testWidget.getElement().setInnerHTML(html);

        int testerWidth = testWidget.getOffsetWidth();
        int newWidth = (testerWidth + comfortZone) >= minWidth ? testerWidth + comfortZone : minWidth;
        int currentWidth = widget.getOffsetWidth();
        boolean isValidWidthChange = (newWidth < currentWidth && newWidth >= minWidth)
                || (newWidth > minWidth);

        int newHeight = testWidget.getOffsetHeight(); // always add a spare

        widget.setHeight(Integer.toString(newHeight) + "px");
        int width;
        if (isValidWidthChange) {
            width = newWidth;
        } else {
            width = currentWidth;
        }
        widget.setWidth(Integer.toString(width) + "px");
        testWidget.getElement().setInnerHTML(""); // for security reasons don't
                                                  // leave hiding data...
        testWidget.getElement().getStyle().setDisplay(Display.NONE);
        return new Point2D(width, newHeight);
    }

    private static void copyTextSizingProps(Style targetStyle, Style widgetStyle) {
        String[] copyProps = new String[] { "fontFamily", "fontSize", "fontWeight", "fontStyle",
                "textTransform", "textDecoration", "letterSpacing", "wordSpacing", "lineHeight", "textAlign",
                "verticalAlign", "direction", "padding", "border", "margin", "whiteSpace" };
        for (String propName : copyProps) {
            targetStyle.setProperty(propName, widgetStyle.getProperty(propName));
        }
    }

    /**
     * Heuristic method to estimate the character position in a text-based
     * widget assuming that the setText method also causes the widget to resize
     * itself to fit the text.
     */
    protected static <T extends Widget & HasText> int estimateCharPos(T widget, int relativeX) {
        String text = widget.getText();
        widget.setText("");
        int i;
        for (i = 0; i < text.length(); i++) {
            widget.setText(widget.getText() + text.charAt(i));
            if (relativeX <= widget.getOffsetWidth()) {
                break;
            }
        }
        return i;
    }

}