TooltipHandler.java

package thinh.eligibleadapter.eventhandler;

import net.minecraft.client.Minecraft;
import net.minecraft.client.gui.FontRenderer;
import net.minecraft.client.gui.ScaledResolution;
import net.minecraft.util.StringUtils;
import net.minecraftforge.client.event.RenderGameOverlayEvent;
import net.minecraftforge.fml.common.eventhandler.SubscribeEvent;
import net.minecraftforge.fml.relauncher.Side;
import net.minecraftforge.fml.relauncher.SideOnly;
import org.lwjgl.opengl.GL11;

import java.awt.*;

public class TooltipHandler {

    /**
     * Abstract
     */
    private static String currentTooltip;
    private static int tooltipDisplayTicks;

    public static void setTooltip(String tooltip) {
        if (!tooltip.equals(currentTooltip)) {
            currentTooltip = tooltip;
            tooltipDisplayTicks = 100;
        }
    }

    @SideOnly(Side.CLIENT)
    @SubscribeEvent
    public void drawTooltipHUD(RenderGameOverlayEvent.Post event) {
        if (event.getType() == RenderGameOverlayEvent.ElementType.ALL && tooltipDisplayTicks > 0 && !StringUtils.isNullOrEmpty(currentTooltip)) {
            Minecraft mc = Minecraft.getMinecraft();
            ScaledResolution scaledResolution = new ScaledResolution(mc);
            int width = scaledResolution.getScaledWidth();
            int height = scaledResolution.getScaledHeight();
            FontRenderer fontRendererObj = mc.fontRendererObj;

            int tooltipX = (width - fontRendererObj.getStringWidth(currentTooltip)) / 2;
            int tooltipY = height - 68;

            int opacity = (int) (tooltipDisplayTicks * 256.0F / 10.0F);

            if (opacity >= 160) {
                opacity = 160;
            }

            if (opacity > 0) {
                GL11.glPushMatrix();
                GL11.glEnable(GL11.GL_BLEND);
                GL11.glBlendFunc(GL11.GL_SRC_ALPHA, GL11.GL_ONE_MINUS_SRC_ALPHA);

                int elapsedTicks = 40;
                int color = Color.getHSBColor((float) Math.cos(elapsedTicks + mc.theWorld.rand.nextInt() / 250D), 0.6F, 1F).getRGB();
                fontRendererObj.drawStringWithShadow(currentTooltip, tooltipX, tooltipY, color + (opacity << 24));

                GL11.glDisable(GL11.GL_BLEND);
                GL11.glPopMatrix();
            }
        }
    }

}