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144 lines (122 loc) · 6.48 KB
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import imgui.*;
import imgui.flag.ImGuiButtonFlags;
import imgui.flag.ImGuiCond;
import imgui.flag.ImGuiMouseButton;
import imgui.flag.ImGuiPopupFlags;
import imgui.type.ImBoolean;
import java.util.ArrayList;
import java.util.List;
public class ExampleCanvasEditor {
private static final List<ImVec2> pointList = new ArrayList<>();
private static final ImVec2 scrolling = new ImVec2();
private static boolean addingLine = false;
public static float thickness = 2.0f;
/**
* Computes the floating-point remainder of a / b.
*
* @param a float
* @param b float
* @return computed floating-point remainder of a / b
*/
private static float fmodf(float a, float b) {
int result = (int) Math.floor(a / b);
return a - result * b;
}
public static void show(final ImBoolean showCanvaWindow) {
ImGui.setNextWindowSize(700, 400, ImGuiCond.Once);
ImGui.setNextWindowPos(ImGui.getMainViewport().getPosX() + 200, ImGui.getMainViewport().getPosY() + 200, ImGuiCond.Once);
if (ImGui.begin("Canvas Demo Window", showCanvaWindow)) {
ImGui.text("This a demo for ImGui Canvas editor");
ImGui.sameLine();
ImGui.text("Mouse Left: drag to add lines,\nMouse Right: drag to scroll, click for context menu.");
// Typically, you would use a BeginChild()/EndChild() pair to benefit from a clipping region + own scrolling.
// Here we demonstrate that this can be replaced by simple offsetting + custom drawing + PushClipRect/PopClipRect() calls.
// To use a child window instead we could use, e.g:
// ImGui.pushStyleVar(ImGuiStyleVar.WindowPadding, 0, 0); // Disable padding
// ImGui.pushStyleColor(ImGuiCol.ChildBg, ImColor.intToColor(50, 50, 50, 255)); // Set a background color
// ImGui.beginChild("canvas", new ImVec2(0.0f, 0.0f), true, ImGuiWindowFlags.NoMove);
// ImGui.popStyleColor();
// ImGui.popStyleVar();
// [...]
// ImGui.endChild();
// Using InvisibleButton() as a convenience 1) it will advance the layout cursor and 2) allows us to use IsItemHovered()/IsItemActive()
ImVec2 canvasP0 = ImGui.getCursorScreenPos(); // ImDrawList API uses screen coordinates!
ImVec2 canvasSize = ImGui.getContentRegionAvail(); // Resize canvas to what's available
if (canvasSize.x < 50.0f) {
canvasSize.x = 50.0f;
}
if (canvasSize.y < 50.0f) {
canvasSize.y = 50.0f;
}
ImVec2 canvasP1 = new ImVec2(canvasP0.x + canvasSize.x, canvasP0.y + canvasSize.y);
// Draw border and background color
ImGuiIO io = ImGui.getIO();
ImDrawList drawList = ImGui.getWindowDrawList();
drawList.addRectFilled(canvasP0.x, canvasP0.y, canvasP1.x, canvasP1.y,
ImColor.rgba(50, 50, 50, 255));
drawList.addRect(canvasP0.x, canvasP0.y, canvasP1.x, canvasP1.y,
ImColor.rgba(255, 255, 255, 255));
// This will catch our interactions
ImGui.invisibleButton("canvas", canvasSize.x, canvasSize.y,
ImGuiButtonFlags.MouseButtonLeft | ImGuiButtonFlags.MouseButtonRight);
boolean isHovered = ImGui.isItemHovered(); // Hovered
boolean isActive = ImGui.isItemActive(); // Held
ImVec2 origin = new ImVec2(canvasP0.x + scrolling.x, canvasP0.y + scrolling.y); // Lock scrolled origin
ImVec2 mousePosInCanvas = new ImVec2(io.getMousePos().x - origin.x, io.getMousePos().y - origin.y);
// Add first and second point
if (isHovered && !addingLine && ImGui.isMouseClicked(ImGuiMouseButton.Left)) {
pointList.add(mousePosInCanvas);
pointList.add(mousePosInCanvas);
addingLine = true;
}
if (addingLine) {
pointList.set(pointList.size() - 1, mousePosInCanvas);
if (!ImGui.isMouseDown(ImGuiMouseButton.Left)) {
addingLine = false;
}
}
// Pan (we use a zero mouse threshold when there's no context menu)
// You may decide to make that threshold dynamic based on whether the mouse is hovering something etc.
float mouseThresholdForPan = -1.0f;
if (isActive && ImGui.isMouseDragging(ImGuiMouseButton.Right, mouseThresholdForPan)) {
scrolling.x += io.getMouseDelta().x;
scrolling.y += io.getMouseDelta().y;
}
// Context menu (under default mouse threshold)
ImVec2 dragDelta = ImGui.getMouseDragDelta(ImGuiMouseButton.Right);
if (dragDelta.x == 0.0f && dragDelta.y == 0.0f) {
ImGui.openPopupOnItemClick("context", ImGuiPopupFlags.MouseButtonRight);
}
// Draw grid + all lines in the canvas
drawList.pushClipRect(canvasP0.x, canvasP0.y, canvasP1.x, canvasP1.y, false);
float GRID_STEP = 64.0f;
for (float x = fmodf(scrolling.x, GRID_STEP); x < canvasSize.x; x += GRID_STEP) {
drawList.addLine(canvasP0.x + x, canvasP0.y, canvasP0.x + x, canvasP1.y,
ImColor.rgba(200, 200, 200, 40));
}
for (float y = fmodf(scrolling.y, GRID_STEP); y < canvasSize.y; y += GRID_STEP) {
drawList.addLine(canvasP0.x, canvasP0.y + y, canvasP1.x, canvasP0.y + y,
ImColor.rgba(200, 200, 200, 40));
}
for (int n = 0; n < pointList.size(); n += 2) {
drawList.addLine(origin.x + pointList.get(n).x, origin.y + pointList.get(n).y,
origin.x + pointList.get(n + 1).x, origin.y + pointList.get(n + 1).y,
ImColor.rgba(255, 255, 0, 255), thickness);
}
drawList.popClipRect();
// Menu properties
if (ImGui.beginPopup("context")) {
addingLine = false;
if (ImGui.menuItem("Remove one", "", false, !pointList.isEmpty())) {
pointList.remove(pointList.size() - 1);
pointList.remove(pointList.size() - 1);
}
if (ImGui.menuItem("Remove all", "", false, !pointList.isEmpty())) {
pointList.clear();
}
ImGui.endPopup();
}
}
ImGui.end();
}
}